AT               Define Absolute Segment                         Combine Type

  segname   SEGMENT AT address

    Specifies an absolute starting address for a segment.  All label and
    addresses in the segment are relative to the specified address.

       Notes:     The parameter address is a 16-bit paragraph starting
                  address for the segment. It can be any valid expression,
                  but must not contain a forward reference.

                  This combine type is usually used as a template for data
                  or code that is at an absolute location in memory, such
                  as the ROM BIOS data area, the interrupt vectors, or the
                  screen buffer.

                  This combine type can not be used to force loading of
                  code or data at a specified location.