d The XREF program will produce a cross-reference listing of a FORTRAN program either by physical line number or by FORTRAN line number. ,  The XREF program will cross-reference each individual subroutine of the input source file, and will also handle the 'INCLUDE' file Xproperly.   Some limitations on the XREF program are.  1) The sizes of the array dimensions are not filled in.  2) The number of elements and the address are zero. L 3) The following statements are not processed by the program  - EXTERNAL  - PARAMETER x - OPEN  - CLOSE @ - DEFINE FILE  - REWIND  - DIRECT ACCESS I/O STATEMENTS l - FUNCTION STATEMENTS  4 Explanation of the XREF output.   For variables that are arrays, you will notice that the dimensions ` are not printed but instead there is a '(-)' , '(-,-)' , or '(-,-,-)' printed in place of the dimensions of the array. ( If a '-' sign appears before the number of 'ARGS' in the list of 'EXTERNALS' then this indicates that the number of arguements T indicated is the maximum number and that one or more of the references to this perticular external has a fewer number of  arguements. If a '>' sign appears after the dimension symbols, then it is an H indication that this array may be referenced in the program with a fewer number of dimension that is indicated here.  t Variables are flagged as:  REF for simple reference < DEFINED for definition by an execution process  DS/DEF for definition by a data statement  POT/DEF for potential definition. Such as the variable is h passed directly to a subroutine or other  external 0  If a local variable is defined only through EQUIVALENCE directly or  indirectly to another variable, which itself is defined by some method \ the '--DEF BY EQUIVALENCE--' will appear in it's references.  $ If a variable is $LOCAL and can not be seen to be defined in any  way, then it will be flagged '**UNDEFINED**'. Sometimes this may  result through a variable simply appearing in a dimension or type P statement and never being used.   Common blocks names are printed under the section column if they | have seven or less characters in their name. Otherwise  (i.e. /-- 4--/) appears indicating, in this case, that it is the D forth common block name to appear in the program being XREFed.   Include statements (non-nested) produce correct reference p numbers by FORTRAN statement numbers only.  8 Tab characters are permitted anywhere within the code, and they  are expanded. If the next character is non-numeric the tab is  expanded so that the character is in column 7. If the next d character is numeric the tab is expanded so that the character  is in column 6. If the tab appears after column 6 it is expanded , to fill the current 8 byte field with blanks.   Lower case characters are converted to upper case before X cross-referencing.    The variables are set according to the desired cross-reference  output L  by Physical line number set  XREF_BY_LINE = .TRUE. & XREF_BY_ISN = .FALSE. x  by Fortran line number @ XREF_BY_LINE = .FALSE. & XREF_BY_ISN = .TRUE.