extensionName

    OpenVMS usage:extension_name
    type:         character-coded text string
    access:       read only
    mechanism:    by descriptor-fixed-length descriptor
    Address of a character string descriptor pointing to the name of
    the extension being looked up.

 extensionID

    OpenVMS usage:extension_ID
    type:         longword (unsigned)
    access:       write only
    mechanism:    by reference
    Address of a longword into which the value of the extension
    identification (EID) returned by the service is written.