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

    VT100: EXT + PF4            VT200: F14
    DEFINE_KEY Function: INSERT_MODE

    Enables insert mode. Use insert mode to edit what you entered. If
    the status display is enabled, Insert appears.

    In insert mode, when you enter a character in to an unprotected
    field, it is displayed to the left of the cursor, moving the
    following one position to the right:

    o  The cursor

    o  The character at the cursor location

    o  All the characters to the right of the cursor in the field

    You can insert characters in to an:

    o  Unformatted screen

    o  Unprotected field on a formatted screen until it is full

    If you attempt to insert characters after the field is full,
    the keyboard locks, the terminal bell rings, and the word Inhib
    appears on the status line. If the keyboard locks when you try
    to insert characters in to a field that looks empty, the field
    might have trailing spaces. To erase these spaces, use the ER EOF
    function.

    To return your screen to the normal mode of entry, use one of the
    following keyboard functions:

    o  RESET

    o  CLEAR

    o  ENTER

    o  Any PA key

    o  Any PF key