/sys$common/syshlp/helplib.hlb MACRO, /MIGRATION, Compiler Directives, .SYMBOL ALIGNMENT, Example  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  OFFSET1 = 4
  .SYMBOL_ALIGNMENT LONG
  OFFSET2 = 8
  OFFSET3 = 12
  .SYMBOL_ALIGNMENT QUAD
  OFFSET4 = 16
  .SYMBOL_ALIGNMENT NONE
  OFFSET5 = 20
      .
      .
      .
  CLR1 OFFSET2(R8)
      .
      .
      .
  MOVL R2, OFFSET4(R6)

      For OFFSET1 and OFFSET5, the compiler will use only its
      tracking information for deciding if Rn in OFFSET1(Rn) is
      aligned or not. For the other references, the base register
      will be treated as longword (OFFSET2 and OFFSET3) or quadword
      (OFFSET4) aligned.

      After each use of OFFSET2 or OFFSET4, the base register in the
      reference is reset to longword alignment. In this example, the
      alignment of R8 and R6 will be reset to longword, although the
      reference to OFFSET4 will use the stronger quadword alignment.