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      3.    Compiler Directives

           Compiler  directives  are instructions to the compiler which are
      inserted in the Pascal source program.  They may be inserted  in  the
      program  anywhere a comment may appear. (Unlike JRT Pascal Version 1,
      they must not be followed by a semicolon delimiter.)


      3.1   Listing Control Directives

           When a Pascal program is being compiled,  the  listing  will  be
      displayed  on  the  system  console.  Five directives are provided to
      control the program listing.

                  %NOLIST   - stop display of program listing

                  %LIST     - resume display of program listing

                  %PAGE     - start a new page in the compiler listing,
                  %PAGE(n)     and optionally set the "lines per page"
                               value to n.

                  %TITLE('string')  - print title at top of each page'
                               activated by first %PAGE directive.


      3.2   Line Trace Directives

           JRT Pascal line  tracing  will  optionally  display  the  source
      program line numbers as the program executes.  The size of the output
      module will be increased by three bytes per line.

                  %LTRACE   - generate line trace codes
                  %NOLTRACE - stop generating line trace codes - this
                               allows storage saving by tracing only
                               a portion of the program.


           JRT  Pascal  line  tracing can be turned on or off under program
      control by using the SYSTEM builtin procedure.   The  range  of  line
      numbers  to  be  traced  can  also  be  modified  at run-time by this
      procedure.  WHEN THE PROGRAM BEGINS  EXECUTION,  THE  LINE  TRACE  IS
      DISABLED.
















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                  SYSTEM( LTRACE )      - activate line trace
                  SYSTEM( NOLTRACE )    - disable line trace
                  SYSTEM( LRANGE, lower, upper )
                                        - set range of line numbers
                                          for line trace - lower and
                                          upper are integer expressions.
           When  a  program is compiled with the %LTRACE directive, then if
      the run-time system detects an error condition, the line number  will
      be displayed with the error message.


      3.3   Procedure Trace Directives

           When  procedure tracing is activated, the name of each procedure
      or function will be displayed on  entry  and  exit.  On  entry  to  a
      procedure  the  activation  count  (total number of times called) for
      that procedure is also listed.

                  %PTRACE         - generated procedure trace codes
                  %NOPTRACE       - stop generating procedure trace
                                     codes


            Procedure tracing can  be  turned  on  and  off  under  program
      control  by  using  the  SYSTEM  builtin procedure.  WHEN THE PROGRAM
      BEGINS EXECUTION, THE PROCEDURE TRACE IS DISABLED.

                  SYSTEM( PTRACE )      - activate procedure trace
                  SYSTEM( NOPTRACE )    - disable procedure trace


           When a program is compiled with the %PTRACE directive,  then  if
      the  run-time system detects an error, the name of the procedure most
      recently activated will be displayed with the  error  message.   NOTE
      that  the  procedure  most  recently activated is not necessarily the
      currently active procedure.

           If the procedure being entered is an external procedure then the
      trace message is flagged with and asterisk.




















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      3.4  Source file INCLUDE directive


           A section of source program code is sometimes used by  different
      main  programs of external procedures.  Rather than enter this common
      code at each point it is  used,  it  is  easier  to  use  a  %INCLUDE
      directive.   This  has  the effect of inserting the named Pascal code
      file in place of the directive.

                 %INCLUDE('filename.typ')


           %INCLUDE files may not be  nested.   This  directive  should  be
      placed on a line by itself.  If the %INCLUDE is indented with spaces,
      then the entire included file is also indented by the same amount.

                 %INCLUDE('GLOBALS.LIB')
                 %INCLUDE('C:VARDCLS.PAS')
                 %INCLUDE('B:SORTPROC.OLD')








































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LIB')
                 %INCLUDE('C:VARDCLS.PAS')
                 %INCLUDE('B:SORTPROC.OLD')