VMS Help MACRO, VAX MACRO Assembler, Directives, .ASCIx, .ASCIZ  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Performs the same function as .ASCII, except that  .ASCIZ  appends
    a null  byte as the final character of the string.  When a list or
    text string is created with an .ASCIZ directive, you need only
    perform  a search  for  the null character in the last byte to
    determine the end of the string.

    .ASCIZ string

    string

    A delimited ASCII string.