The Match Characters, Return Relative Position routine searches a
    source string for a specified substring and returns an index,
    which is the relative position of the first occurrence of a
    substring in the source string. The relative character positions
    returned by LIB$MATCHC are numbered 1, 2, . . . , n. Thus, zero
    means that the substring was not found.

    Format

      LIB$MATCHC  sub-string ,source-string

1 - Returns

    OpenVMS usage:longword_unsigned
    type:         longword (unsigned)
    access:       write only
    mechanism:    by value

    The relative position of the first character of the substring if
    found, or zero if not found.

2 - Arguments

 sub-string

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

    Substring to be found. The sub-string argument is the address of
    a descriptor pointing to this substring.

 source-string

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

    Source string to be searched by LIB$MATCHC. The source-string
    argument is the address of a descriptor pointing to this source
    string.