VMS Help MACRO, VAX MACRO Assembler, Operand Formats  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Operands for  instructions  identify  the  memory  locations  or
    the registers  that  are  used  by the machine operation.  These
    operands specify the addressing mode for the instruction.

  Additional Information (explode) :

• Absolute
• Autodecrement
• Autoincrement
• Autoincrement deferred
• Branch
• Displacement
• Displacement deferred
• General
• Immediate or Literal
• Indexed
• Register
• Register deferred
• Relative
• Relative deferred