VMS Help TCPIP Services, TELNET, TN3270 Keyboard Functions, FM  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    VT100: EXT + ;              VT200: EXT + F13
    DEFINE_KEY Function: FM

    Specifies the end of a field on an unformatted screen or the end
    of part of an unprotected field on a formatted screen. Refer to
    the user's guide of the remote application program for specific
    use of this key.

    Displays a semicolon ( ; ).