DOS Unit            Unit General Description
 Flag Constants      Flag register test bits
 File Modes          Constants used when opening/closing files.
 File Attributes     Constant declarations for file attributes
 File Records        Record type definitions for file types
 Registers           Type definition for Intr and MsDos Procedures
 DateTime            Type definition for Date and Time procedures
 SearchRec           Type definition for FindFirst and FindNext procedures
 DosError            Error messages returned by DosError