first-source-string

    OpenVMS usage:char_string
    type:         character string
    access:       read only
    mechanism:    by descriptor

    First source string. The first-source-string argument is the
    address of a descriptor pointing to the first source string.

 second-source-string

    OpenVMS usage:char_string
    type:         character string
    access:       read only
    mechanism:    by descriptor

    Second source string. The second-source-string argument is the
    address of a descriptor pointing to the second source string.