VMS Help MERGE, Specification File Qualifiers, /KEY, Qualifier Values  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 field-name

    Specifies the name of the key field. The field-name has been
    previously specified in a /FIELD qualifier.

 order

    Specifies the order of the sort. The ASCENDING option specifies
    ascending order for a sort or merge operation. This option is the
    default. The DESCENDING option specifies descending order for a
    sort or merge operation.

 value

    Specifies the key. The value can be a constant or a field-name
    that has been defined in a /FIELD qualifier.