Provides conditional execution of a  debugger  command.   If  the
     language  expression  given in the IF clause is true, the command
     given in the THEN clause is executed.  If the language expression
     is false, and an ELSE clause is present, the command given in the
     ELSE clause is executed.

     This feature is primarily useful in debugger  command  procedures
     and in the DO clause of breakpoints.

 Format:

     IF lang-exp THEN (debug-cmd-list) [ELSE (debug-cmd-list)]

     Example:

     DBG> SET BRE/SILENT X DO (IF Y .NE. 3 THEN (GO))
     ! The above is equivalent to:
     DBG> SET BRE/SILENT X WHEN (Y .EQ. 3)

Additional information available:

Parameters

 lang-exp

     Any expression in the currently set language which  evaluates  to
     TRUE  or  FALSE.  For example, (X .EQ.  5) in FORTRAN, or (Y[3] >
     2) in PASCAL.  See "HELP Languages *" for information  about  the
     syntax of each language.

 debug-cmd-list

     A single debugger command or  a  sequence  of  debugger  commands
     separated by semicolons.