DOS                 Operating system and file handling routines
  Flag Constants      Flag register test bits
  File Mode            Constants used when opening/closing files.
  File Attributes     File attribute constants
  File Record         File record types
  Register Type       Type definition for Intr and MsDos Procedures
  Date/Time Type      Definition for PackTime and UnPackTime
  SearchRec Type      FindFirst and FindNext data Types
  DosError            Error messages returned by DosError