2bH set system date             2eH   set/query disk verify level
2dH set system time             3300H query Break-checking level
57H query time/date of a file   3301H set Break-checking level

25H set interrupt vector
35H query interrupt vector

30H   query DOS Version (as set via SetVer)
3306H query actual DOS Version

50H set current process ID
51H query current process ID
34H get InDOS and ErrorMode addresses

2fH query Disk Transfer Address (DTA)
1aH set Disk Transfer Address (DTA)

37H set the DOS command line switch character  obsolete 

Miscellaneous DOS Functions