Library /sys$common/syshlp/dbg$help.hlb DEBUG, SET, BREAK, Qualifiers, /INSTRUCTION  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /INSTRUCTION
       /INSTRUCTION[=(opcode[, . . . ])]

    When you do not specify an opcode, causes the debugger to break
    on every instruction encountered during program execution.

    On VAX processors only, you can optionally specify one or more
    opcodes. This causes the debugger to break on every instruction
    with an opcode that is on the list.

    If you specify a vector instruction (VAX only), do not include
    an instruction qualifier (/UNALIGNED_DATA, /VECTOR_INSTRUCTION,
    /MODIFY, /0, or /1) with the instruction mnemonic.

    See also the /INTO and /OVER qualifiers.