record locking question - pretty urgent

[Fairlight]

I need to design a mechanism for something, and I need to know the answer
to something about record locking as a result.

Let's say you had 20 clerk processes all running concurrently.  Let's also
say they need exclusive access to a single record in a table.  

1) You use a protected lookup, right?

2) If process #3 has the protected lookup, do the other processes gain the
ability to grab that record instantly, if they're all waiting on the record
lock?

3) As the next process grabs the locked record, is it -assured- that only
-one- of those processes will grab the lock, forcing the rest to wait for
the same condition, where the current process releases the locked record?
Basically, is prevention of a race condition guaranteed?

Thanks,

mark->
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