And the article on Jazz at: 
http://jazz.external.hp.com/papers/Communicator/5.5/exp3/ci_enhancements
.html#LISTF

describes some of the file locks that can be detected.

"4) If the process does not have any locks then "NONE" is displayed. If
the PIN owns or is waiting on one or more of the relevant semaphores
then the semaphore name is shown under either the "Owner" or Waiter"
column. There are three semaphores (locks) considered.

The FLOCK semaphore, which is obtained when a processes calls the FLOCK
intrinsic. This lock is exclusive meaning that only one process at a
time can own the FLOCK semaphore for a file. Occasionally the FLOCK
semaphore is used by the file system to to synchronize directory access.

The OPEN semaphore is locked by the file system when a file is being
formally opened. In this usage the OPEN semaphore is locked exclusively.
It is also used by the operating system to protect certain file system
data structures when they are being read. This usage allows the OPEN
semaphore to be locked in a shared fashion. The OPEN semaphore can be
locked shared by multiple processes, but once it is locked exclusively
all other PINs trying to lock it will wait.

The GUFD semaphore is locked by the file system when it does I/O on the
target file. It is locked exclusively."
...

Hope this helps,
 Jeff Vance, vCSY
 
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