Screen Functions:

    The Expand library now provides a number of screen handling functions.
    The Clipper documentation suggests the application developer only to
    use the Clipper Terminal system for any Video I/O, and the Expand respects
    those guidelines as all functions presented in this section make use
    of the Clipper SaveScreen() and RestScreen() functions, and of the
    Expand Internal DelAttr() and ReplAttr() functions (Written in Assembly),
    which perform primitive operations on the Strings returned by
    SaveScreen().

    This makes it possible to have efficient Screen handling functions
    and respect the Nantucket guidelines concerning Video I/O.

    Note that these functions will therefore not work when the IBM terminal
    system (Clipper default) is not used, as some drivers will not support
    saving and restoring screens.