FOREIGN  DEFINITION MODULE SysClock;
  IMPORT IMPLEMENTATION FROM "sysclock.obj";

  (* ========================================================= *)
  (* Preliminary module for Gardens Point Modula               *)
  (* Proposed BSI/ISO Standard Modula-2 Library                *)
  (* copyright assigned by R. Sutcliffe to BSI                 *)
  (* version 1990 12 14                                        *)
  (* Permission is given to copy this Definition Module, with  *)
  (* the copy  right  notice intact,  for the  purpose of      *)
  (* evaluation and test.                                      *)
  (* Status : for review by ISO/IEC STC1/SC22/WG13             *)
  (* Note : This module may change form in the future          *)
  (* ========================================================= *) 
  
  CONST
   maxSecondParts = 99;  (* implementation defined constant *)
   (* The value here implies the clock delivers 0.01 second *)
  
  TYPE
   Month = [1 .. 12];
   Day = [1 ..31];
   Hour = [0 .. 23];
   Min = [0 .. 59];
   Sec = [0 .. 59];
   Fraction = [0 .. maxSecondParts]; (* parts of a second *)
   UTCDiff = [-780 .. 720];    (* Time zone Differential Factor *)
           (* the number of minutes that must be added to local time to
              obtain UTC.   *)
   DateTime =
     RECORD
       year   : CARDINAL;
       month  : Month;
       day    : Day;
       hour   : Hour;
       minute : Min;
       second : Sec;
       fractions: Fraction;
       zone    : UTCDiff;
       SummerTimeFlag : BOOLEAN;  (* interpretation: local usage *)
    END;
  
  PROCEDURE CanGetClock () : BOOLEAN;
  (* Tests if a clock can be read *)
  
  PROCEDURE CanSetClock () : BOOLEAN;
  (* Tests if a clock can be set *)
  
  PROCEDURE IsValidDateTime (userData : DateTime) : BOOLEAN;
  (* Tests if the value of userData is a valid *)
  
  PROCEDURE GetClock (VAR userData : DateTime);
  (* Assigns local date and time of day to userData *)
  
  PROCEDURE SetClock (userData : DateTime);
  (* Sets the system clock to the given local date and time *)
  
  END SysClock.