NAME
	LockRecord -- Locks a portion of a file (V36)

   SYNOPSIS
	success = LockRecord(fh,offset,length,mode,timeout)
	D0                   D1   D2     D3    D4    D5

	BOOL LockRecord(BPTR,ULONG,ULONG,ULONG,ULONG)

   FUNCTION
	This locks a portion of a file for exclusive access.  Timeout is how
	long to wait in ticks (1/50 sec) for the record to be available.

	Valid modes are:
		REC_EXCLUSIVE
		REC_EXCLUSIVE_IMMED
		REC_SHARED
		REC_SHARED_IMMED
	For the IMMED modes, the timeout is ignored.

	Record locks are tied to the filehandle used to create them.  The
	same filehandle can get any number of exclusive locks on the same
	record, for example.  These are cooperative locks, they only
	affect other people calling LockRecord().

   INPUTS
	fh      - File handle for which to lock the record
	offset  - Record start position
	length  - Length of record in bytes
	mode    - Type of lock requester
	timeout - Timeout interval in ticks.  0 is legal.

   RESULT
	success - Success or failure

   BUGS
	In 2.0 through 2.02 (V36), LockRecord() only worked in the ramdisk.
	Attempting to lock records on the disk filesystem causes a crash.
	This was fixed for V37.

   SEE ALSO
	LockRecords(), UnLockRecord(), UnLockRecords()