1.DBG> SHOW SOURCE
      no directory search list in effect,
          match the latest source file version
      DBG> SET SOURCE [PROJA],[PROJB],DISK:[PETER.PROJC]
      DBG> SHOW SOURCE
      source directory search list for all modules,
          match the latest source file version:
              [PROJA]
              [PROJB]
              DISK:[PETER.PROJC]
      DBG>

      In this example, the SET SOURCE command directs the debugger to
      search the directories [PROJA],[PROJB], and DISK:[PETER.PROJC].
      By default, the debugger searches for the latest version of
      source files.

    2.DBG> SET SOURCE/MODULE=CTEST/EXACT [], DISK$2:[PROJD]
      DBG> SHOW SOURCE
      source directory search list for CTEST,
          match the exact source file version:
              []
              DISK$2:[PROJD]
      source directory search list for all other modules,
      match the latest source file version:
              [PROJA]
              [PROJB]
              DISK:[PETER.PROJC]
      DBG>

      In this example, the SET SOURCE command directs the debugger
      to search the current default directory ([]) and directory
      DISK$2:[PROJD] for source files to use with the module CTEST.
      The /EXACT qualifier specifies that the search will locate
      the exact version of the CTEST source files found in the debug
      symbol table.