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The next part of the GAMS output is the symbol cross reference map. This lists the named items (Sets, Parameters, Variables, Equations, Models, Files, Acronyms) in alphabetical order, identifies them as to type, shows the line numbers where the symbols appear, and classifies each appearance.
The symbol reference map for the shortmodel.gms example is
SYMBOL TYPE REFERENCES
AVAILABLE EQU declared 23 defined 26 impl-asn 29
ref 28
OBJT EQU declared 22 defined 24 impl-asn 29
ref 28
ite ACRNM declared 36 defined 36
PRICE PARAM declared 8 defined 9 ref 24
PROCESS SET declared 6 defined 6 ref 8
10 12 16 20 2*24 2*25
26 27 control 24 26
PRODCOST PARAM declared 12 defined 13 ref 25
PRODUCTION VAR declared 20 impl-asn 29 ref 25
27
PROFIT VAR declared 21 impl-asn 29 ref 24
29
putfile FILE declared 37 defined 38
RESALLOC MODEL declared 28 defined 28 impl-asn 29
ref 29
RESORAVAIL PARAM declared 14 defined 15 ref 27
RESOURCE SET declared 7 defined 7 ref 14
16 23 26 27 control 26
RESOURUSE PARAM declared 16 defined 16 ref 26
solprod PARAM ref 34 38
Yield PARAM declared 10 defined 11 ref 24
The symbol column is an all inclusive alphabetical list of all named items in the GAMS program. The type column gives a categorical classification of the basic nature of the symbol using abbreviation codes as follows
TYPE
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Type of GAMS item
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ACRNM
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Acronym
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EQU
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Equation
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FILE
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Put file
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MODEL
|
Model
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PARAM
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Parameter (also Table, Scalar)
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SET
|
Set
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VAR
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Variable
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The symbol map also contains a line number indexed list of references to the items, grouped by type of reference which are abbreviated as below
Reference
|
Description
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DECLARED
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This identifies lines where the named item is declared in a Set, Parameter, Table, Scalar, Variable, Equation, Acronym, File or Model command. This will be the first appearance.
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DEFINED
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This identifies the line number where explicit data are entered (in a table or a data list between slashes) or in the case of an equation where the .. specification begins.
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ASSIGNED
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This identifies lines where this item has data put into it by being on the left hand side of an assignment statement.
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IMPL-ASN
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This identifies lines where an equation or variable has data put into it by the results of a solve statement.
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CONTROL
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This identifies lines where this set is used as the driving index either in an assignment, equation, loop or other indexed operation (sum, prod, smin or smax).
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REF
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This identifies lines where this item is used either on the right hand side of an assignment, in a display, in an equation, in a model, in a put statement or in a solve statement.
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Notes:
| • | The symbol cross reference map does not always appear. In particular, it is suppressed by default in the IDE and, if desired, needs to be requested by using the command 6. |
| • | In GAMS Dos and Unix the reference map always appears and if one wishes to suppress it one uses $Offsymxref. |
| • | The reference map is often large and not always useful given the capabilities of today's text editors. It is usually suppressed in most models (with $Offsymxref). |
| • | This map can be useful in model development, documentation preparation, and to make sure you do not have items that are present but never used (insuring all items have ref, impl-asn, or control entries present). |
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