I2GRID - VECTOR TO RASTER CONVERSION

MODULE I2GRID

Vector to Raster Conversion

Issue 3.0 - 9 March 1989
Copyright (C) 1988  Laser-Scan Ltd
Science Park, Milton Road, Cambridge, England CB4 4FY  tel: (0223) 420414
Document "I2GRID Reference"   Category "Reference"
Document Issue  3.0 D R Catlow              09-March-1989
  Issue  2.0 D R Catlow              21-December-1988
  Issue  1.2     D R Catlow              19-August-1988
  Issue  1.1     D R Catlow              12-May-1988 
         Issue 1.0 D R Catlow  17-October-1986


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MODULE I2GRID

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FUNCTION

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FORMAT

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PROMPTS

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DESCRIPTION

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DATA CONVERSION

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OUTPUT DTI MATRIX

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OUTPUT ATTRIBUTE SELECTION

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OUTPUT DATA TYPE

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OUTPUT PRIORITY

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MATRIX BACKGROUND

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USE WITH DFAD DATA

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I2GRID COMMANDS

COMMAND LIST

The following commands are defined :


	@		!		AREA FC		AREA FRT	
	ATTRIBUTE AC	ATTRIBUTE FC	ATTRIBUTE FSN	ATTRIBUTE Z	
	BACKGROUND	CREATE		DATA_TYPE	DESELECT FC	
	DESELECT FSN	DESELECT LAYER	DISABLE ABSOLUTE
	DISABLE DFAD	DISABLE LOG	DISABLE PRESET	DISABLE THICK	
	DISABLE TRUNCATE 		ENABLE ABSOLUTE ENABLE DFAD 	
	ENABLE LOG	ENABLE PRESET	ENABLE THICK 	ENABLE TRUNCATE	
	EXIT		FRT		GO		GRID	
	HEADER_TYPE	HELP 		IFF		IFFWINDOW 
	OPEN 		PRESET FC	PRESET FSN	PRIORITY CURRENT
	PRIORITY FIRST	PRIORITY LARGEST		PRIORITY SMALLEST
	RETURN		SELECT ALL	SELECT FC	SELECT FSN	
	SELECT LAYER	SHOW ENABLE	SHOW IFF	SHOW PARAMETERS	
	SHOW PRESET	SHOW SELECTIONS	SPAWN		WAIT		
	WIDTH
	
	

_@ COMMAND

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_@

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FORMAT: _@ file-spec

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Command parameters:

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DESCRIPTION:

I2GRID offers the facility of command input from an indirect command file. The '@' character preceding a file-spec will cause I2GRID to open and read commands from the specified file until:

Nested command files are not supported (i_.e_. a command file containing an '@' command), although sequential '@' commands are supported when read from SYS$COMMAND.

As an aid to batch log interpretation I2GRID will echo all commands read from an indirect command file.

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Messages:

The following messages are specific to the _@ command:


*** ERROR *** Specifying command @
Command file specification is missing

*** ERROR *** Specifying command @
Unable to open indirect command file 'file-spec'

*** ERROR *** Specifying command @
Nested command files not supported

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Examples:


I2GRID> @I2GRID_EDITS
I2GRID> ENABLE LOG
I2GRID> ENABLE TRUNCATE
I2GRID> PRESET FC 1-50 = 100
I2GRID> RETURN
I2GRID>

_! COMMAND

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_!

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FORMAT: _! [comment text]

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Command parameters:

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DESCRIPTION:

An exclamation mark is the standard TVES package comment delimiter. All text (and numbers) which lie to the right of a '!' character are excluded from command interpretation. Comments are useful for annotating command procedures used in batch processing etc.

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Messages: None.

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Examples:


I2GRID> ENABLE TRUNCATE !truncate attribute values<CR>
I2GRID> !enable the log option<CR>
I2GRID> ENABLE LOG<CR>
I2GRID>

AREA FC COMMAND

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AREA FC

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FORMAT:		AREA FC feature_code [,...]

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Command parameters:

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DESCRIPTION:

The AREA FC command is used to identify features in the IFF file that are to be treated as area features by I2GRID. Using this command area features are defined on the basis of their feature code.

When scan converting area features, both the boundary cells and the cells interior to the feature are coded with the selected attribute value.

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Messages:

The following error messages are specific to the AREA and AREA FC commands:


*** ERROR *** Specifying command AREA
Command qualifiers are FC or FRT

*** ERROR *** Specifying command AREA
Command requires a list of integer feature code values

*** ERROR *** Specifying command AREA
Illegal feature code value

*** ERROR *** Specifying command AREA
Second part of feature code range is missing

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Examples:

I2GRID>AREA FC 10,20-30 40
I2GRID>

AREA FRT COMMAND

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AREA FRT

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FORMAT:		AREA FRT

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Command parameters: _None

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DESCRIPTION:

The AREA FRT command is used to identify features in the IFF file that are to be treated as area features by I2GRID. Using this command, area features are identified on the basis of the graphical type entry in a FRT file. Graphical Type 12 indicates an area feature.

When scan converting area features, both the boundary cells and the cells interior to the feature are coded with the selected attribute value.

If this option is selected, a FRT must have been previously defined using the FRT command. It should be noted though that on giving the FRT command, AREA FRT is assumed by default.

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Messages:

The following error messages are specific to the AREA and AREA FRT commands:


*** ERROR *** Specifying command AREA
Command qualifiers are FC or FRT

*** ERROR *** Specifying command AREA
No FRT file has been specified

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Examples:

I2GRID>AREA FRT
I2GRID>

ATTRIBUTE AC COMMAND

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ATTRIBUTE AC

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FORMAT:		ATTRIBUTE AC ac_type [text]
	        		

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Command parameters:

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DESCRIPTION:

The ATTRIBUTE command is used to define which IFF feature attribute is transferred to the output DTI matrix when the GO command is given. Only a single attribute value may be output per feature.

The command ATTRIBUTE AC specifies that the attribute is the value associated with an AC of the specified type. Eg. the command ATTRIBUTE AC 2, or alternatively ATTRIBUTE AC CONTOUR, will transfer the height value associated with a contour AC. The AC may be an AC predefined by LSL, or may be an AC defined by the user in an ACD table in an FRT file. In the latter case, the command FRT must have been previously given to read in an FRT.

The ACD data type determines the format of the AC value. I2GRID will transfer only integer or real AC data values.

If the optional text string is given, then a value associated with that text string in the text field of the AC, is transferred to the output matrix. Eg. the command ATTRIBUTE AC DFAD_FADT HGT will select the output of a value from the AC text field, associated with the text string HGT.

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Messages:

The following error messages are specific to the ATTRIBUTE and ATTRIBUTE AC commands:


*** ERROR *** Specifying command ATTRIBUTE
Valid qualifiers are AC, FC, FSN or Z

*** ERROR *** Specifying command ATTRIBUTE AC
Command requires an integer AC type number or AC name

*** ERROR *** Specifying command ATTRIBUTE AC
AC  not found in ACD table

*** ERROR *** Specifying command ATTRIBUTE AC
AC  not found in ACD table

*** ERROR *** Specifying command ATTRIBUTE AC
Unable to use ACD  
Associated value is not integer or real

*** ERROR *** Specifying command ATTRIBUTE AC
Unable to read the associated text string

Output of AC   value selected

Output of AC    value selected

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Examples:

I2GRID>ATTRIBUTE AC CONTOUR

Output of AC Contour(2) value selected

I2GRID>ATTRIBUTE AC DFAD_FADT HGT
Output of AC DFAD_FADT(7) HGT value selected

ATTRIBUTE FC COMMAND

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ATTRIBUTE FC

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FORMAT:		ATTRIBUTE FC
	        		

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Command parameters: _None

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DESCRIPTION:

The ATTRIBUTE command is used to define which IFF feature attribute is transferred to the output DTI matrix when the GO command is given. Only a single attribute value may be output per feature.

The command ATTRIBUTE FC specifies that the attribute is the feature code. Eg. if the FC is 10, then a value of 10 will be recorded in the output DTI file.

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Messages:

The following messages are specific to the ATTRIBUTE command:


*** ERROR *** Specifying command ATTRIBUTE
Valid qualifiers are AC, FC, FSN or Z

Output of FC value selected

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Examples:

I2GRID>ATTRIBUTE FC

Output of FC value selected

I2GRID>

ATTRIBUTE FSN COMMAND

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ATTRIBUTE FSN

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FORMAT:		ATTRIBUTE FSN
	        		

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Command parameters: _None

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DESCRIPTION:

The ATTRIBUTE command is used to define which IFF feature attribute is transferred to the output DTI matrix when the GO command is given. Only a single attribute value may be output for a feature.

The command ATTRIBUTE FSN specifies that the attribute is the feature serial number. Eg. if the FSN is 10, then a value of 10 will be recorded in the output DTI file.

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Messages:

The following messages are specific to the ATTRIBUTE command:


*** ERROR *** Specifying command ATTRIBUTE
Valid qualifiers are AC, FC, FSN or Z

Output of FSN value selected

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Examples:

I2GRID>ATTRIBUTE FSN

Output of FSN value selected

I2GRID>

ATTRIBUTE Z COMMAND

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ATTRIBUTE Z

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FORMAT:		ATTRIBUTE Z
	        		

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Command parameters: _None

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DESCRIPTION:

The ATTRIBUTE command is used to define which IFF feature attribute is transferred to the output DTI matrix when the GO command is given. Only a single attribute value may be output per feature.

The command ATTRIBUTE Z specifies that the attribute is a height value derived from the Z coordinates of an IFF feature. For an area feature, a height associated with the first coordinate point is transferred to the output matrix. For a linear feature, the height value associated with each coordinate point is used, and the heights of any intermediary matrix points are derived using linear interpolation.

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Messages:

The following messages are specific to the ATTRIBUTE command:


*** ERROR *** Specifying command ATTRIBUTE
Valid qualifiers are AC, FC, FSN or Z

Output of Z coordinate values selected

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Examples:

I2GRID>ATTRIBUTE Z

Output of Z coordinate values selected

I2GRID>

BACKGROUND COMMAND

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BACKGROUND

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FORMAT:		BACKGROUND  value

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Command parameters:

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DESCRIPTION:

The BACKGROUND command allows a value to be assigned to the background matrix points in the output DTI file. A background matrix point is a point that is not encoded during the vector to raster conversion process. By default the matrix background is given a value of 0.

A background value may only be assigned if conversion is to a new output DTI file specified using the CREATE command. The background value of an existing DTI file cannot be changed.

The background value defined using the BACKGROUND command is validated against the output DTI file data type when the GO command is given. An error message is generated if the background value is too large or too small.

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Messages:

The following error message is specific to the BACKGROUND command:


*** ERROR *** Specifying command BACKGROUND
Command requires an integer or real argument

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Example:

I2GRID>BACKGROUND 23
I2GRID>

CREATE COMMAND

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CREATE

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FORMAT:		CREATE file-spec
	        		

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Command parameters:

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DESCRIPTION:

The CREATE command specifies the name of a DTI file that will be created when the GO command is given, and into which the gridded attribute data will be encoded.

The grid interval values for this file are specified using the GRID command, while the DATA_TYPE and HEADER_TYPE commands may be used to specify the format of the data values and DTI header. The dimensions of the output DTI file (ie. the number of columns and rows), are calculated using the IFF range or IFFWINDOW values, and the matrix grid interval values.

If data is to be encoded into an existing matrix, the OPEN command should be used.

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Messages:

The following error message is specific to the CREATE command:


*** ERROR *** Specifying command CREATE
DTI filename is missing

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Example:

I2GRID>CREATE FORESTS
I2GRID>

DATA_TYPE COMMAND

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DATA_TYPE

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FORMAT:		DATA_TYPE format
	        		

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Command parameters:

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DESCRIPTION:

The DATA_TYPE command may be used to control the format in which the encoded attribute data is held in the output DTI file. The command is only applicable if output is to a new DTI file specified using the CREATE command. If output is to an existing file using the OPEN command, the data type is derived from the header of this file, and cannot be redefined.

By default the attribute values are output as a word in the range -32768 to 32767.

The ENABLE TRUNCATE command controls whether an attribute value that is too small or too large to be stored in the data type, is truncated to fit, or is rejected during the vector to raster conversion process.

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Messages:

The following error message is specific to the DATA_TYPE command:


*** ERROR *** Specifying command DATA_TYPE
Valid qualifiers are BIT, BYTE, LONGWORD, WORD or REAL

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Example:

I2GRID>DATA_TYPE BYTE
I2GRID>

DESELECT FC COMMAND

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DESELECT FC

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FORMAT:         DESELECT FC feature_code [,...]

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Command parameters:

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DESCRIPTION:

The DESELECT FC command is used to exclude IFF features from conversion. Features are excluded on the basis of their feature code.

By default I2GRID will convert all features within an IFF file.

Use of the SHOW SELECTIONS command is recommended to display feature selections before the GO command is given.

Deselection on the basis of group name is valid only if the FRT command has been used to previously read a Feature Representation Table.

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Messages:

The following error messages are specific to the DESELECT and DESELECT FC commands:


*** ERROR *** Specifying command DESELECT
Command qualifiers are FC, FSN, or LAYER             

*** ERROR *** Specifying command DESELECT
Illegal feature code

*** ERROR *** Specifying command DESELECT FC
No FRT has been read

*** ERROR *** Specifying command DESELECT FC
No groups have been defined in the FRT

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Examples:

I2GRID>DESELECT FC 1
I2GRID>DESELECT FC RAILWAYS
I2GRID>DESELECT FC RIVERS 7-10,56-78
I2GRID>

DESELECT FSN COMMAND

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DESELECT FSN

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FORMAT:	        DESELECT FSN fsn [,...]

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Command parameters:

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DESCRIPTION:

The DESELECT FSN command is used to exclude IFF features from conversion. Features are excluded on the basis of their feature serial number.

By default I2GRID will convert all features within an IFF file.

Use of the SHOW SELECTIONS command is recommended to display feature selections before the GO command is given.

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Messages:

The following error messages are specific to the DESELECT and DESELECT FSN commands:


*** ERROR *** Specifying command DESELECT
Command qualifiers are FC, FSN, or LAYER             

*** ERROR *** Specifying command DESELECT FSN
Illegal FSN number

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Examples:

I2GRID>DESELECT FSN 4
I2GRID>DESELECT FSN 7-10,56-78
I2GRID>

DESELECT LAYER COMMAND

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DESELECT LAYER

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FORMAT:	        DESELECT LAYER layer [,...]

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Command parameters:

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DESCRIPTION:

The DESELECT LAYER command is used to exclude IFF features from conversion. Features are excluded on the basis of IFF layer.

By default I2GRID will convert all features within an IFF file.

Use of the SHOW SELECTIONS command is recommended to display feature selections before the GO command is given.

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Messages:

The following error messages are specific to the DESELECT and DESELECT LAYER commands:


*** ERROR *** Specifying command DESELECT
Command qualifiers are FC, FSN, or LAYER             

*** ERROR *** Specifying command DESELECT
Illegal layer number

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Examples:

I2GRID>DESELECT LAYER 7
I2GRID>DESELECT LAYER 1,7-10
I2GRID>

DISABLE ABSOLUTE COMMAND

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DISABLE ABSOLUTE

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FORMAT:	        DISABLE ABSOLUTE

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Command parameters: _None

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DESCRIPTION:

The DISABLE ABSOLUTE cancels a previous ENABLE ABSOLUTE command. If DISABLE ABSOLUTE is specified, then IFF coordinates supplied with the IFFWINDOW command are interpreted as values relative to the IFF local origin.

The command also controls how IFF coordinates are displayed when the SHOW IFF command is given.

By default the use of absolute coordinate values is enabled.

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Messages:

The following error message is specific to the DISABLE command:


*** ERROR *** Specifying command DISABLE
Command qualifiers are ABSOLUTE, DFAD, LOG, PRESET, THICK or TRUNCATE

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Examples:

I2GRID>DISABLE ABSOLUTE
I2GRID>

DISABLE DFAD COMMAND

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DISABLE DFAD

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FORMAT:	        DISABLE DFAD

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Command parameters: _None

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DESCRIPTION:

The DISABLE DFAD command cancels a previous ENABLE DFAD command, and deselects the options that are appropriate to the conversion of DLMS DFAD data. If the command is given, then the options and rules that are applied when converting IFF features, are set to program startup defaults.

The defaults are:

Use of the SHOW PARAMETERS command is recommended to check on the status of these various options before the GO command is given.

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Messages:

The following error message is specific to the DISABLE command:


*** ERROR *** Specifying command DISABLE
Command qualifiers are ABSOLUTE, DFAD, LOG, PRESET, THICK or TRUNCATE

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Examples:

I2GRID>DISABLE DFAD
I2GRID>

DISABLE LOG COMMAND

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DISABLE LOG

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FORMAT:	        DISABLE LOG

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Command parameters: _None

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DESCRIPTION:

DISABLE LOG disables the output of informational and warning messages to the terminal as each IFF feature is converted.

By default the LOG messages are enabled.

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Messages:

The following error message is specific to the DISABLE command:


*** ERROR *** Specifying command DISABLE
Command qualifiers are ABSOLUTE, DFAD, LOG, PRESET, THICK or TRUNCATE

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Examples:

I2GRID>DISABLE LOG
I2GRID>

DISABLE PRESET COMMAND

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DISABLE PRESET

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FORMAT:	        DISABLE PRESET

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Command parameters: _None

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DESCRIPTION:

The DISABLE PRESET command disables the use of the values pre-assigned to features by means of the PRESET command. When the GO command is given to initiate the vector to raster conversion all PRESET values will be ignored, and the output matrix will be encoded with a value determined by means of the ATTRIBUTE command.

By default any pre-assigned values defined using the PRESET command will be used.

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Messages:

The following error message is specific to the DISABLE command:


*** ERROR *** Specifying command DISABLE
Command qualifiers are ABSOLUTE, DFAD, LOG, PRESET, THICK or TRUNCATE

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Examples:

I2GRID>DISABLE PRESET
I2GRID>

DISABLE THICK COMMAND

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DISABLE THICK

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FORMAT:	        DISABLE THICK

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Command parameters: _None

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DESCRIPTION:

The DISABLE THICK command controls whether a thickness value is applied to a linear feature before conversion.

If DISABLE THICK is specified then all linear features are represented by a line of minimum thickness (single pixel wide) in the output matrix.

By default THICK is disabled.

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Messages:

The following error messages is specific to the DISABLE command:


*** ERROR *** Specifying command ENABLE
Command qualifiers are ABSOLUTE, DFAD, LOG, PRESET, THICK or TRUNCATE

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Examples:

I2GRID>DISABLE THICK
I2GRID>

DISABLE TRUNCATE COMMAND

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DISABLE TRUNCATE

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FORMAT:	        DISABLE TRUNCATE

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Command parameters: _None

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DESCRIPTION:

The DISABLE TRUNCATE command deselects the option of truncating attribute values if they are either too small or too large to be stored in the output DTI file. Any IFF feature whose attribute value is too small or too large will be rejected, and will not be scan converted.

If the ENABLE LOG command has been given a warning message will be output.

By default values will be truncated.

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Messages:

The following error message is specific to the DISABLE command:


*** ERROR *** Specifying command DISABLE
Command qualifiers are ABSOLUTE, DFAD, LOG, PRESET, THICK or TRUNCATE

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Examples:

I2GRID>DISABLE TRUNCATE
I2GRID>

ENABLE ABSOLUTE COMMAND

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ENABLE ABSOLUTE

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FORMAT:	        ENABLE ABSOLUTE

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Command parameters: _None

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DESCRIPTION:

The ENABLE ABSOLUTE command selects the use of absolute IFF coordinate values. If ENABLE ABSOLUTE is specified, then values supplied with the IFFWINDOW command are interpreted as absolute IFF coordinates.

The command also controls how IFF coordinates are displayed when the SHOW IFF command is given.

By default the use of absolute coordinate values is enabled.

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Messages:

The following error message is specific to the ENABLE command:


*** ERROR *** Specifying command ENABLE
Command qualifiers are ABSOLUTE, DFAD, LOG, PRESET, THICK or TRUNCATE

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Examples:

I2GRID>DISABLE ABSOLUTE
I2GRID>

ENABLE DFAD COMMAND

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ENABLE DFAD

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FORMAT:	        ENABLE DFAD

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Command parameters: _None

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DESCRIPTION:

The ENABLE DFAD command selects various options that are appropriate to the conversion of DLMS DFAD data. If the command is given then the following rules are applied by default, when converting the IFF data:

Use of the SHOW PARAMETERS command is recommended to check on the status of these various options before the GO command is given.

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Messages:

The following error message is specific to the ENABLE command:


*** ERROR *** Specifying command ENABLE
Command qualifiers are ABSOLUTE, DFAD, LOG, PRESET, THICK or TRUNCATE

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Examples:

I2GRID>ENABLE DFAD
I2GRID>

ENABLE LOG COMMAND

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ENABLE LOG

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FORMAT:	        ENABLE LOG

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Command parameters: _None

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DESCRIPTION:

ENABLE LOG enables the output of informational and warning messages to the terminal as each IFF feature is converted. These messages indicate whether a feature has been successfully converted, and the value of its associated attribute.

By default the output of LOG messages is enabled.

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Messages:

The following error message is specific to the ENABLE command:


*** ERROR *** Specifying command ENABLE
Command qualifiers are ABSOLUTE, DFAD, LOG, PRESET, THICK or TRUNCATE

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Examples:

I2GRID>ENABLE LOG
I2GRID>

ENABLE PRESET COMMAND

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ENABLE PRESET

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FORMAT:	        ENABLE PRESET

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Command parameters: _None

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DESCRIPTION:

The ENABLE PRESET command enables the use of the values pre-assigned to features by means of the PRESET command. By default, or if this command is given, any value preassigned to a feature on the basis of feature code of FSN, is used rather than the attribute value.

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Messages:

The following error message is specific to the ENABLE command:


*** ERROR *** Specifying command ENABLE
Command qualifiers are ABSOLUTE, DFAD, LOG, PRESET, THICK or TRUNCATE

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Examples:

I2GRID>ENABLE PRESET
I2GRID>

ENABLE THICK COMMAND

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ENABLE THICK

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FORMAT:	        ENABLE THICK

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Command parameters: _None

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DESCRIPTION:

The ENABLE THICK command controls whether a thickness value is applied to a linear feature before conversion.

If ENABLE THICK is specified then all linear features are thickened by an amount specified using the WIDTH command. The width is specified in IFF units. The actual representation of a thickened line in the output matrix depends upon the size of this value, and on the output matrix grid interval.

By default the option to thicken lines is disabled.

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Messages:

The following error messages are specific to the ENABLE command:


*** ERROR *** Specifying command ENABLE
Command qualifiers are ABSOLUTE, DFAD, LOG, PRESET, THICK or TRUNCATE

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Examples:

I2GRID>ENABLE THICK
I2GRID>

ENABLE TRUNCATE COMMAND

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ENABLE TRUNCATE

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FORMAT:	        ENABLE TRUNCATE

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Command parameters: _None

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DESCRIPTION:

The ENABLE TRUNCATE command controls whether attribute values are truncated so that they may be stored in the output DTI file, if they are either too small or too large.

If ENABLE TRUNCATE is specified the attribute values will be truncated. For example, if output is to a DTI file holding byte data, an attribute value of 340 will be truncated to 255, and an attribute value of -10 to 0, before encoding.

When outputting to a BIT, BYTE, WORD or LONGWORD data file, a real attribute value is converted to the nearest integer, before truncating.

By default values will be truncated. The option may be disabled using the DISABLE TRUNCATE command.

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Messages:

The following error messages are specific to the ENABLE command:


*** ERROR *** Specifying command ENABLE
Command qualifiers are ABSOLUTE, DFAD, LOG, PRESET, THICK or TRUNCATE

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Examples:

I2GRID>ENABLE TRUNCATE
I2GRID>

EXIT COMMAND

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EXIT

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FORMAT:		 EXIT

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Command parameters: None.

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DESCRIPTION:

The EXIT command is used to exit from I2GRID.
(pressing the Ctrl and Z keys together) may also be used to exit from the program.

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Messages: None.

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Examples:

I2GRID>EXIT
$

FRT COMMAND

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FRT

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FORMAT:	        FRT  file-spec

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Command parameters:

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DESCRIPTION:

This command reads the specified Feature Representation Table. The FRT is used to determine which IFF features are to be treated as areas during the conversion process (a graphical type of 12 indicates an area feature), and to define group names and user specified ACDs.

The commands SELECT FC 'group', AREA FRT and ATTRIBUTE AC 'user ACD' require a FRT to have been previously selected.

If the FRT command is given, then I2GRID assumes by default that areas are to be defined on the basis of FRT graphical type. This is equivalent to giving the command AREA FRT. The command AREA FC may be used to override this default.

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Messages:

The following error message is specific to the FRT command:


*** ERROR *** Specifying command FRT
Input FRT filename is missing

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Examples:

I2GRID>FRT LSL.FRT
I2GRID>

GO COMMAND

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GO

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FORMAT:		GO

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Command parameters: _None

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DESCRIPTION:

This command initiates the vector to raster conversion process.

An input IFF file must have been previously defined using the IFF command, and an output DTI file using the OPEN or CREATE commands. If the CREATE command has been used, then the x and y grid interval of the output file must also have been previously defined by means of the GRID command.

If the BACKGROUND command has been given, then a check is made before conversion proceeds, that the background value is valid for the output DTI data type.

Successful conversion is indicated by the display of DTI header details (including the minimum and maximum data values), and by the I2GRID> prompt on the terminal.

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Messages:

The following messages are specific to the GO command:


*** ERROR *** Specifying command GO
No output DTI file has been defined
Use the command OPEN or CREATE

*** ERROR *** Specifying command GO
No input IFF file has been defined
Use the command IFF

*** ERROR *** Specifying command GO
Matrix grid intervals are not defined
Use the command GRID

*** ERROR *** Specifying command GO
Background value invalid for output data type
Redefine the value using the BACKGROUND command

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Example:

I2GRID>GO



I2GRID>

GRID COMMAND

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GRID

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FORMAT:	        GRID column_interval row_interval

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Command parameters:

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DESCRIPTION:

The GRID command defines the output matrix column and row grid interval values. The command is only required if conversion is to a new output DTI file specified using the CREATE command; if conversion is to an existing DTI file the grid interval values in the header of this file are used.

The grid interval values are used to determine in conjunction with the IFF range or IFFWINDOW values, the dimensions (ie. number of columns and rows) of the output matrix. It is important that grid values are chosen carefully to avoid excessively large output DTI files being produced, and according to the application of the gridded data.

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Messages:

The following error messages are specific to the GRID command:


*** ERROR *** Specifying command GRID
Command requires 2 arguments

*** ERROR *** Specifying command GRID
Command requires 2 real numbers greater than 0

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Examples:

I2GRID>GRID 2.5 3.5
I2GRID>

HEADER_TYPE COMMAND

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HEADER_TYPE

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FORMAT:		HEADER_TYPE format
	        		

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Command parameters:

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DESCRIPTION:

The HEADER_TYPE command may be used to define the header format of the output DTI file. The command is only applicable if output is to a new DTI file specified using the CREATE command. If output is to an existing file using the OPEN command, the header type is derived from this file, and cannot be changed.

If output is to a DTI file with a LSLA header, projection information is transferred from the IFF Map Descriptor to the DTI Projection Record. If output is to a UHL1 DTI file, a blank UHL1 header record is created. If output is to a TED4 DTI file, blank DSI and ACC records are inserted into the file header.

By default a DTI file with a LSLA header is created.

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Messages:

The following error message is specific to the HEADER_TYPE command:


*** ERROR *** Specifying command HEADER_TYPE
Valid qualifiers are LSLA, UHL1 or TED4

--------------------------------------------------------------------------------
Example:

I2GRID>HEADER_TYPE TED4
I2GRID>

HELP COMMAND

--------------------------------------------------------------------------------
HELP

--------------------------------------------------------------------------------

FORMAT:		 HELP [command]

--------------------------------------------------------------------------------
Command parameters:

--------------------------------------------------------------------------------
DESCRIPTION:

A brief description is given of the function and format of the specified command.
If no parameter is supplied then a list of all commands available is given.

--------------------------------------------------------------------------------
Messages: None.

--------------------------------------------------------------------------------
Examples:

I2GRID>HELP CREATE
I2GRID>

IFF COMMAND

--------------------------------------------------------------------------------
IFF

--------------------------------------------------------------------------------

FORMAT:	        IFF  file-spec

--------------------------------------------------------------------------------
Command parameters:

--------------------------------------------------------------------------------
DESCRIPTION:

The IFF command specifies the name of an Internal Feature Format file, containing the vector data that is to be converted to a grid representation.

On opening the IFF file, a default area of interest equivalent to the IFF coordinate range is set. This may be subsequently altered using the IFFWINDOW command. The IFF range or IFFWINDOW values, in conjunction with the output matrix grid interval values, determine the dimensions (number of columns and rows) of the output DTI file.

The IFF filename, file range and current IFF window may be examined using the command SHOW IFF.

--------------------------------------------------------------------------------
Messages:

The following error message is specific to the IFF command:


*** ERROR *** Specifying command IFF
Input IFF filename is missing

--------------------------------------------------------------------------------
Examples:

I2GRID>IFF TEST



I2GRID>

IFFWINDOW COMMAND

--------------------------------------------------------------------------------
IFFWINDOW

--------------------------------------------------------------------------------

FORMAT:	        IFFWINDOW swx swy nex ney

--------------------------------------------------------------------------------
Command parameters:

--------------------------------------------------------------------------------
DESCRIPTION:

IFFWINDOW is used to define a rectangular area of interest within the IFF file. Only IFF features that lie within this area are converted.

By default or if the ENABLE ABSOLUTE command has been given then window values should be supplied in absolute IFF units. Otherwise coordinates should be specified as values relative to the IFF file local origin.

The IFFWINDOW values, in conjunction with the output matrix grid interval values, determine the dimensions (number of columns and rows) of the output DTI file.

The IFF filename, file range and current IFF window may be examined using the command SHOW IFF.

--------------------------------------------------------------------------------
Messages:

The following error messages are specific to the IFFWINDOW command:


*** ERROR *** Specifying command IFFWINDOW
No IFF file is open

*** ERROR *** Specifying command IFFWINDOW
NE corner should exceed SW corner

--------------------------------------------------------------------------------
Examples:

I2GRID>IFFWINDOW 310000 220000 270000 180000
I2GRID>

OPEN COMMAND

--------------------------------------------------------------------------------
OPEN

--------------------------------------------------------------------------------

FORMAT:		OPEN file-spec
	        		

--------------------------------------------------------------------------------
Command parameters:

--------------------------------------------------------------------------------
DESCRIPTION:

The OPEN command specifies the name of an existing DTI file that will be opened when the GO command is given, and into which the gridded attribute data will be encoded.

The header type, data type and grid interval values are read from the header of this file, and cannot be reset using the commands HEADER_TYPE, DATA_TYPE and GRID. Similarly the BACKGROUND command cannot be used to change the file's existing background data value.

--------------------------------------------------------------------------------
Messages:

The following error message is specific to the OPEN command:


*** ERROR *** Specifying command OPEN
DTI filename is missing

--------------------------------------------------------------------------------
Example:

I2GRID>OPEN FORESTS
I2GRID>

PRESET FC

--------------------------------------------------------------------------------
PRESET FC

--------------------------------------------------------------------------------

FORMAT:		PRESET FC feature_code [,...] = data_value
	        		

--------------------------------------------------------------------------------
Command parameters:

--------------------------------------------------------------------------------
DESCRIPTION:

The PRESET FC command is used to assign a preset value to particular IFF features. Features are assigned a preset value on the basis of feature code. The preset data value is output in preference to any value associated with the currently selected attribute.

The PRESET FC command may be given a number of times to assign different preset data values to a different set of feature codes.

Use of the PRESET values may be enabled or disabled using the ENABLE and DISABLE PRESET commands. By default use of the PRESET values is enabled.

The current settings may be examined by means of the SHOW PRESET command.

--------------------------------------------------------------------------------
Messages:

The following error messages are specific to the PRESET and PRESET FC command:


*** ERROR *** Specifying command PRESET
Valid qualifiers are FC or FSN

*** ERROR *** Specifying command PRESET
Unexpected end of line
Missing = delimiter

*** ERROR *** Specifying command PRESET
Unexpected end of line
Missing preset value

*** ERROR *** Specifying command PRESET
Unexpected end of line
Second part of range missing

*** ERROR *** Specifying command PRESET
Unable to read preset value

*** ERROR *** Specifying command PRESET
Missing FC or FSN values

*** ERROR *** Specifying command PRESET
Unable to read FC or FSN value

--------------------------------------------------------------------------------
Example:

I2GRID>PRESET FC 10-20,34 = 10
I2GRID>PRESET FC 1,2,3 = 64
I2GRID>

PRESET FSN

--------------------------------------------------------------------------------
PRESET FSN

--------------------------------------------------------------------------------

FORMAT:		PRESET FSN fsn [,...] = data_value
	        		

--------------------------------------------------------------------------------
Command parameters:

--------------------------------------------------------------------------------
DESCRIPTION:

The PRESET FSN command is used to assign a preset value to particular IFF features. Features are assigned a preset value on the basis of feature serial number. The preset data value is output in preference to any value associated with the currently selected attribute.

The PRESET FSN command may be given a number of times to assign different preset data values to a different IFF features.

Use of the PRESET values may be enabled or disabled using the ENABLE and DISABLE PRESET commands. By default use of the PRESET values is enabled.

The current settings may be examined by means of the SHOW PARAMETERS command.

--------------------------------------------------------------------------------
Messages:

The following error messages are specific to the PRESET and PRESET FSN command:


*** ERROR *** Specifying command PRESET
Valid qualifiers are FC or FSN

*** ERROR *** Specifying command PRESET
Unexpected end of line
Missing = delimiter

*** ERROR *** Specifying command PRESET
Unexpected end of line
Missing preset value

*** ERROR *** Specifying command PRESET
Unexpected end of line
Second part of range missing

*** ERROR *** Specifying command PRESET
Unable to read preset value

*** ERROR *** Specifying command PRESET
Missing FC or FSN values

*** ERROR *** Specifying command PRESET
Unable to read FC or FSN value

--------------------------------------------------------------------------------
Example:

I2GRID>PRESET FSN 10-20,34 = 10
I2GRID>PRESET FSN 1,2,3 = 64
I2GRID>

PRIORITY CURRENT

--------------------------------------------------------------------------------
PRIORITY CURRENT

--------------------------------------------------------------------------------

FORMAT:		PRIORITY CURRENT

--------------------------------------------------------------------------------
Command parameters: None.

--------------------------------------------------------------------------------
DESCRIPTION:

The PRIORITY command determines what action will be taken if more than one IFF coordinate references the same point in the output matrix.

If PRIORITY CURRENT is specified then the value recorded at the matrix position is always the attribute associated with the current IFF feature. A previous matrix value may therefore be overwritten during conversion, and the final matrix value depends on the order in which features are arranged in the IFF file.

Use of the SHOW PARAMETERS command is recommended to check on the current PRIORITY option before the GO command is given.

The introduction contains further explanation and guidance on the use of the PRIORITY command.

--------------------------------------------------------------------------------
Messages:

The following error message is specific to the PRIORITY command:


*** ERROR *** Specifying command PRIORITY
Valid qualifiers are CURRENT, FIRST, LARGEST or SMALLEST

--------------------------------------------------------------------------------
Example:

I2GRID>PRIORITY CURRENT
I2GRID>

PRIORITY FIRST COMMAND

--------------------------------------------------------------------------------
PRIORITY FIRST

--------------------------------------------------------------------------------

FORMAT:		PRIORITY FIRST

--------------------------------------------------------------------------------
Command parameters: None.

--------------------------------------------------------------------------------
DESCRIPTION:

The PRIORITY command determines what action will be taken if more than one IFF coordinate references the same point in the output matrix.

If PRIORITY FIRST is specified then the attribute associated with the first feature in the IFF file to reference the point, is used. An existing matrix value will not be overwritten by any other value.

Use of the SHOW PARAMETERS command is recommended to check on the current PRIORITY option before the GO command is given.

The introduction contains further explanation and guidance on the use of the PRIORITY command.

--------------------------------------------------------------------------------
Messages:

The following error message is specific to the PRIORITY command:


*** ERROR *** Specifying command PRIORITY
Valid qualifiers are CURRENT, FIRST, LARGEST or SMALLEST

--------------------------------------------------------------------------------
Example:

I2GRID>PRIORITY FIRST
I2GRID>

PRIORITY LARGEST

--------------------------------------------------------------------------------
PRIORITY LARGEST

--------------------------------------------------------------------------------

FORMAT:		PRIORITY LARGEST

--------------------------------------------------------------------------------
Command parameters: None.

--------------------------------------------------------------------------------
DESCRIPTION:

The PRIORITY command determines what action will be taken if more than one IFF coordinate references the same point in the output matrix.

If PRIORITY LARGEST is specified then the value recorded at the matrix position is the largest attribute value encountered. A previous matrix value may therefore be overwritten during conversion.

Use of the SHOW PARAMETERS command is recommended to check on the current PRIORITY option before the GO command is given.

The introduction contains further explanation and guidance on the use of the PRIORITY command.

--------------------------------------------------------------------------------
Messages:

The following error message is specific to the PRIORITY command:


*** ERROR *** Specifying command PRIORITY
Valid qualifiers are CURRENT, FIRST, LARGEST or SMALLEST

--------------------------------------------------------------------------------
Example:

I2GRID>PRIORITY LARGEST
I2GRID>

PRIORITY SMALLEST

--------------------------------------------------------------------------------
PRIORITY SMALLEST

--------------------------------------------------------------------------------

FORMAT:		PRIORITY SMALLEST

--------------------------------------------------------------------------------
Command parameters: None.

--------------------------------------------------------------------------------
DESCRIPTION:

The PRIORITY command determines what action will be taken if more than one IFF coordinate references the same point in the output matrix.

If PRIORITY SMALLEST is specified then the value recorded at the matrix position is the smallest attribute value encountered. A previous matrix value may therefore be overwritten during conversion.

Use of the SHOW PARAMETERS command is recommended to check on the current PRIORITY option before the GO command is given.

The introduction contains further explanation and guidance on the use of the PRIORITY command.

--------------------------------------------------------------------------------
Messages:

The following error message is specific to the PRIORITY command:


*** ERROR *** Specifying command PRIORITY
Valid qualifiers are CURRENT, FIRST, LARGEST or SMALLEST

--------------------------------------------------------------------------------
Example:

I2GRID>PRIORITY SMALLEST
I2GRID>

RETURN COMMAND

--------------------------------------------------------------------------------
RETURN

--------------------------------------------------------------------------------
FORMAT: RETURN

--------------------------------------------------------------------------------
Command parameters: None.

--------------------------------------------------------------------------------
DESCRIPTION:

Restores command input from an indirect command file to SYS$COMMAND.

A typical application is to use an indirect command file to set up a number of run time defaults for a flowline, and then return to input from the terminal for the run specific commands. To do this RETURN must be the last command in the indirect command file.

A RETURN command is only valid if present in a command file.

--------------------------------------------------------------------------------
Messages:

The following messages are specific to the RETURN command:


*** ERROR *** Specifying command RETURN
The RETURN command is only valid in a command file

Returning to terminal input

--------------------------------------------------------------------------------
Examples:


I2GRID> @SETUP<CR>
I2GRID> CREATE TEST
I2GRID> GRID 10 10
I2GRID> RETURN
Returning to terminal input
I2GRID>

SELECT ALL COMMAND

--------------------------------------------------------------------------------
SELECT ALL

--------------------------------------------------------------------------------

FORMAT:	        SELECT ALL

--------------------------------------------------------------------------------
Command parameters: _None

--------------------------------------------------------------------------------
DESCRIPTION:

SELECT ALL resets all IFF feature selections made using any of the SELECT or DESELECT commands.

--------------------------------------------------------------------------------
Message:

The following error messages are specific to the SELECT command:


*** ERROR *** Specifying command SELECT
Command qualifiers are ALL, FC, FSN or LAYER

--------------------------------------------------------------------------------
Examples:

I2GRID>SELECT ALL
I2GRID>SELECT FSN 7-10,56-78
I2GRID>SHOW SELECTIONS



I2GRID>SELECT ALL
I2GRID>SHOW SELECTIONS


I2GRID>

SELECT FC COMMAND

--------------------------------------------------------------------------------
SELECT FC

--------------------------------------------------------------------------------

FORMAT:         SELECT FC feature_code [,...]

--------------------------------------------------------------------------------
Command parameters:

--------------------------------------------------------------------------------
DESCRIPTION:

The SELECT FC command is used to include an IFF feature for conversion. Features are included on the basis of their feature code.

By default I2GRID will convert all features within an IFF file.

Use of the SHOW SELECTIONS command is recommended to check on feature selections before the GO command is given.

Selection on the basis of group name is valid only if the FRT command has been used to previously read a Feature Representation Table.

--------------------------------------------------------------------------------
Messages:

The following error messages are specific to the SELECT command:


*** ERROR *** Specifying command SELECT
Command qualifiers are ALL, FC, FSN, or LAYER             

--------------------------------------------------------------------------------
Examples:

I2GRID>SELECT FC 1
I2GRID>SELECT FC RAILWAYS
I2GRID>SELECT FC RIVERS 7-10,56-78<CR>
I2GRID>

SELECT FSN COMMAND

--------------------------------------------------------------------------------
SELECT FSN

--------------------------------------------------------------------------------

FORMAT:	        SELECT FSN fsn [,...]

--------------------------------------------------------------------------------
Command parameters:

--------------------------------------------------------------------------------
DESCRIPTION:

The SELECT FSN command is used to include IFF features for conversion. Features are included on the basis of their feature serial number.

By default I2GRID will use all features within an IFF file.

Use of the SHOW SELECTIONS command is recommended to display feature selections before the GO command is given.

--------------------------------------------------------------------------------
Messages:

The following error messages are specific to the SELECT command:


*** ERROR *** Specifying command SELECT
Command qualifiers are ALL, FC, FSN, or LAYER             

--------------------------------------------------------------------------------
Examples:

I2GRID>SELECT FSN 4
I2GRID>SELECT FSN 7-10,56-78
I2GRID>

SELECT LAYER COMMAND

--------------------------------------------------------------------------------
SELECT LAYER

--------------------------------------------------------------------------------

FORMAT:	        SELECT LAYER layer [,...]

--------------------------------------------------------------------------------
Command parameters:

--------------------------------------------------------------------------------
DESCRIPTION:

The SELECT LAYER command is used to include IFF features for conversion. Features are included on the basis of IFF layer.

By default I2GRID will use all features within an IFF file.

Use of the SHOW SELECTIONS command is recommended to display feature selections before the GO command is given.

--------------------------------------------------------------------------------
Messages:

The following error messages are specific to the SELECT command:


*** ERROR *** Specifying command SELECT
Command qualifiers are ALL, FC, FSN, or LAYER             

--------------------------------------------------------------------------------
Examples:

I2GRID>SELECT LAYER 15
I2GRID>SELECT LAYER 1,7-10
I2GRID>

SHOW ENABLE COMMAND

--------------------------------------------------------------------------------
SHOW ENABLE

--------------------------------------------------------------------------------

FORMAT:		 SHOW ENABLE

--------------------------------------------------------------------------------
Command parameters: None.

--------------------------------------------------------------------------------
DESCRIPTION:

Displays the current status of all the I2GRID options that may be enabled or disabled using the ENABLE and DISABLE commands.

The name of the option is shown, followed by either the word ON or OFF to indicate its current status.

If the command SHOW ENABLE is used before any ENABLE or DISABLE commands have been given, the default status of the options is displayed.

--------------------------------------------------------------------------------
Messages:

The following message is specific to the SHOW command:


*** ERROR *** Specifying command SHOW
Command qualifiers are ENABLE, IFF, PARAMETERS, PRESET or SELECTIONS

--------------------------------------------------------------------------------
Examples:

I2GRID>SHOW ENABLE


Current status:

ABSOLUTE         On        DFAD 	    Off	       LOG	      On

PRESET		 On	   THICK	    Off	       TRUNCATE       On


I2GRID>

SHOW IFF COMMAND

--------------------------------------------------------------------------------
SHOW IFF

--------------------------------------------------------------------------------

FORMAT:		 SHOW IFF

--------------------------------------------------------------------------------
Command parameters: None.

--------------------------------------------------------------------------------
DESCRIPTION:

Displays information on the currently selected IFF file.

The name of the IFF file, and the IFF coordinate range and window settings are shown. By default or if the ENABLE ABSOLUTE command has been given, the coordinates are expressed as absolute values. If the DISABLE ABSOLUTE command has been given, the values are displayed relative to the IFF local origin.

--------------------------------------------------------------------------------
Messages:

The following messages are specific to the SHOW and SHOW IFF commands:


*** ERROR *** Specifying command SHOW
Command qualifiers are ENABLE, IFF, PARAMETERS, PRESET or SELECTIONS

*** WARNING *** The input IFF file is undefined

--------------------------------------------------------------------------------
Examples:

I2GRID>SHOW IFF


IFF file:       LSL$IF:TEST.IFF

IFF file range:
SW: 270000.00 180000.00   NE: 310000.00  220000.00
IFF file window :
SW: 280000.00 190000.00   NE: 320000.00  190000.00


I2GRID>

SHOW PARAMETERS COMMAND

--------------------------------------------------------------------------------
SHOW PARAMETERS

--------------------------------------------------------------------------------

FORMAT:		 SHOW PARAMETERS

--------------------------------------------------------------------------------
Command parameters: None.

--------------------------------------------------------------------------------
DESCRIPTION:

The SHOW PARAMETERS command displays information on those parameters controlling the format of the output DTI file, and how an attribute value is encoded in the matrix.

Information is given on the output DTI filename, header and data type and matrix grid interval. Details are also provided on the selected IFF attribute and priority, and on how area features are to be identified.

--------------------------------------------------------------------------------
Messages:

The following message is specific to the SHOW command:


*** ERROR *** Specifying command SHOW
Command qualifiers are ENABLE, IFF, PARAMETERS, PRESET or SELECTIONS

--------------------------------------------------------------------------------
Examples:

I2GRID>SHOW PARAMETERS




I2GRID>

SHOW PRESET COMMAND

--------------------------------------------------------------------------------
SHOW PRESET

--------------------------------------------------------------------------------

FORMAT:		 SHOW PRESET

--------------------------------------------------------------------------------
Command parameters: None.

--------------------------------------------------------------------------------
DESCRIPTION:

The SHOW PRESET command displays a list of feature codes or feature serial numbers that have been preassigned a value using the PRESET command.

--------------------------------------------------------------------------------
Messages:

The following message is specific to the SHOW command:


*** ERROR *** Specifying command SHOW
Command qualifiers are ENABLE, IFF, PARAMETERS, PRESET or SELECTIONS

--------------------------------------------------------------------------------
Examples:

I2GRID>PRESET FSN 1-3 = 100
I2GRID>SHOW PRESET


Features with the following codes have pre-assigned values:

Features with the following FSNs  have pre-assigned values:
FSN         :      1 - 3      Value:   100.000


I2GRID>

SHOW SELECTIONS

--------------------------------------------------------------------------------
SHOW SELECTIONS

--------------------------------------------------------------------------------
Command parameters: _None

--------------------------------------------------------------------------------

FORMAT:		 SHOW SELECTIONS

--------------------------------------------------------------------------------
DESCRIPTION:

The SHOW SELECTIONS command displays information about current IFF feature selections made with the SELECT and DESELECT commands.

--------------------------------------------------------------------------------
Messages:

The following message is specific to the SHOW command:


*** ERROR *** Specifying command SHOW
Command qualifiers are ENABLE, IFF, PARAMETERS, PRESET or SELECTIONS

--------------------------------------------------------------------------------
Examples:

I2GRID>SHOW SELECTIONS

All Layers selected
All Feature Codes selected
All FSNs selected

I2GRID>

SPAWN COMMAND

--------------------------------------------------------------------------------
SPAWN

--------------------------------------------------------------------------------
FORMAT: SPAWN command-line

--------------------------------------------------------------------------------
Command parameters:

--------------------------------------------------------------------------------
DESCRIPTION:

The SPAWN command enables you to create a subprocess while within I2GRID. When the subprocess terminates, control is returned to I2GRID.

--------------------------------------------------------------------------------
Messages:

The following error messages are specific to the SPAWN command:


*** ERROR *** Specifying command SPAWN 
Command requires a valid DCL command line

*** ERROR *** Specifying command SPAWN 
DCL command line cannot exceed 80 characters

*** ERROR *** Unable to spawn command, returning to I2GRID

--------------------------------------------------------------------------------
Examples:

I2GRID> SPAWN DIRECTORY LSL$DTI:*_._DTI

Directory DUA3:[LSL.DTI]
TEST1_.DTI;1              8/8       18-AUG-1987 07:56  [LSL,DAVEC]
TEST2_.DTI;1              7/8       18-AUG-1987 17:17  [LSL,DAVEC]
TEST2_.DTI;2              7/8       18-AUG-1987 17:34  [LSL,DAVEC]
Total of 3 files, 22/24 blocks.

I2GRID>

WAIT COMMAND

--------------------------------------------------------------------------------
WAIT

--------------------------------------------------------------------------------
FORMAT: WAIT seconds

--------------------------------------------------------------------------------
Command parameters:

--------------------------------------------------------------------------------
DESCRIPTION:

The WAIT command causes processing to be suspended for a specified number of seconds. It is designed for use in software demonstration situations and is of no value in a production flowline.

--------------------------------------------------------------------------------
Messages:

The following error message is specific to the WAIT command:


*** ERROR *** Specifying command WAIT
Command requires a real argument

--------------------------------------------------------------------------------
Examples:


I2GRID> WAIT 4.0<CR>
I2GRID>

WIDTH

--------------------------------------------------------------------------------
WIDTH

--------------------------------------------------------------------------------

FORMAT:	        WIDTH width

--------------------------------------------------------------------------------
Command parameters:

--------------------------------------------------------------------------------
DESCRIPTION:

The WIDTH command is used to specify a width or line thickness value that is applied to linear IFF features prior to scan conversion.

The width is specified in IFF units, and results in a thicker representation of the feature in the output matrix. The exact representation is dependent on the output matrix grid intervals.

To produce a thickened representation of a line, I2GRID converts a linear feature into an area feature with the required thickness prior to scan conversion. Care should be taken that an excessively large width value is not applied to sinuous line features since a poor representation of the thickened line in the output matrix may result.

The option to apply the width value to linear features may be disabled using the DISABLE THICK command. It may be enabled again using the ENABLE THICK command.

--------------------------------------------------------------------------------
Messages:

The following error message is specific to the WIDTH command:


*** ERROR *** Specifying command WIDTH
Command requires a positive real argument

--------------------------------------------------------------------------------
Examples:

I2GRID>WIDTH 4
I2GRID>

EXAMPLE I2GRID SESSIONS

--------------------------------------------------------------------------------

EXAMPLE I2GRID SESSION


$ I2GRID
TVES module I2GRID of 12:49:09 23-DEC-88
I2GRID> IFF TEST
%LSLLIB-I-IFFOPENED, LSL$IF:TEST.IFF;1 opened for read

LSL$IF:TEST.IFF;0

IFF file range:
SW:       0.0       0.0  NE:      20.0      20.0
IFF file window :
SW:       0.0       0.0  NE:      20.0      20.0

I2GRID> GRID 1 1
I2GRID> DATA BYTE
I2GRID> CREATE TEST
I2GRID> ATTRIBUTE FC
Output of Feature Code selected
I2GRID> GO
Feature      1 converted   value      5
Feature      2 converted   value      5
Feature      3 converted   value      3

File    :  LSL$DTI:TEST.DTI
Header  :  LSLA  Data:  BYTE

Units are DTI matrix values

Matrix Coverage   SW:     1     1  NE:    21    21
Matrix Interval    E:     1         N:     1
Value Range         :     0   to      5

I2GRID> EXIT
 ELAPSED:    0 00:01:39.78  CPU: 0:00:01.18  BUFIO: 56  DIRIO: 17  FAULTS: 196 

In this example, the IFF file LSL$IF:TEST.IFF is selected as the input IFF containing the vector data to be rasterised. Output is to a new DTI file with the file specification LSL$DTI:TEST.DTI. This file will be created when the GO command is given.
The DATA_TYPE command is used to specify that the attribute data will be transferred to the output file in byte format, in the range 0 through 255. Since DISABLE TRUNCATE has not been specified, any data values greater than this limit will be truncated to fit. The output DTI file will be created by default with a LSLA header structure, and any projection information will be transferred from the IFF file to the DTI file.
The GRID command controls the resolution of the rasterised data, and is used by the program to calculate the number of columns and rows in the output DTI file. If output is to a new DTI file this command must always be given before the GO command.
The ATTRIBUTE FC command has been used to select the transfer the output of the IFF feature code to the DTI file.


$I2GRID
TVES module I2GRID of 12:49:09 23-DEC-88
I2GRID> IFF TEST
%LSLLIB-I-IFFOPENED, LSL$IF:TEST.IFF;1 opened for read

LSL$IF:TEST.IFF;0

IFF file range:
SW:       0.0       0.0  NE:      20.0      20.0
IFF file window :
SW:       0.0       0.0  NE:      20.0      20.0

I2GRID> GRID 1 1
I2GRID> DATA BYTE
I2GRID> BACKGROUND 10
I2GRID> CREATE TEST
I2GRID> PRESET FSN 1-3 = 100
I2GRID> SHOW PRESET

Features with the following codes have pre-assigned values:

Features with the following FSNs  have pre-assigned values:
FSN         :      1 - 3      Value:   100.000

I2GRID> GO
Feature      1 converted   value    100
Feature      2 converted   value    100
Feature      3 converted   value    100

File    :  LSL$DTI:TEST.DTI
Header  :  LSLA  Data:  BYTE

Units are DTI matrix values

Matrix Coverage   SW:     1     1  NE:    21    21
Matrix Interval    E:     1         N:     1
Value Range         :    10   to    100

I2GRID> EXIT
 ELAPSED:    0 00:01:02.23  CPU: 0:00:01.53  BUFIO: 53  DIRIO: 12  FAULTS: 332 

In this example, the IFF file LSL$IF:TEST.IFF is selected as the input IFF containing the vector data to be rasterised. Output is to a new DTI file with the file specification LSL$DTI:TEST.DTI. This file will be created when the GO command is given. The DATA_TYPE command is used to specify that the attribute data will be transferred to the output file in byte format, in the range 0 through 255. The background command has been used to initialise all the matrix points to 10 before the encoding operation begins. The output DTI file will be created by default with a LSLA header structure, and any projection information will be transferred from the IFF file to the DTI file.
The GRID command controls the resolution of the rasterised data, and is used by the program to calculate the number of columns and rows in the output DTI file. If output is to a new DTI file this command must always be given before the GO command.
The PRESET FSN command has been used to assign a value of 100 with FSNs 1, 2 and 3. This value will be transferred to the DTI file rather than an attribute value when these features are processed.

MESSAGES (OTHER)

--------------------------------------------------------------------------------

MESSAGES (OTHER)

In addition to messages which are generated by the program itself, other messages may be produced by Laser-Scan libraries. In particular, messages may be generated the IFF Library, DTI library, and by the Laser-Scan I/O library, LSLLIB.

IFF library messages are introduced by '%IFF', and are documented in the IFF library users' guide.DTI library messages are introduced by '%DTI', and are documented in the DTILIB Reference Manual. In all cases the messages indicate a fatal error, that will cause processing to halt.

LSLLIB messages are introduced by '%LSLLIB' and are generally self-explanatory. Such messages rarely indicate a fatal error, and are generated most frequently by entering a command in an invalid format in response to the I2GRID prompt.