Int 21 Fn 99  u - European MS-dos 4.0 - "pblock" - Block A Process         [D]

   AH = 99h
   DS:BX -> memory location to block on
   CX = timeout in milliseconds
   DH = nonzero if interruptable

Return: CF clear if awakened by event
       AX = 0000h
   CF set if unusual wakeup
       ZF set if timeout, clear if interrupted by signal
       AX = nonzero
Desc:  suspend calling process until another process sends a "restart" signal
     or a timeout occurs

See Also: AH=9Ah,INT 2F/AX=0802h