Do inter-process pipes use secondary (disc) memory for buffering?

[G.SWIFT]

Recently, some controversy has arisen in my group regarding whether
interprocess pipes use primary (main) or secondary (disc) memory for buffering.
Our best guess is that buffering is done internally in the operating
system, however, there are some that believe that since a file descriptor
is returned by the pipe sytem call that this indicates that a disc file
is being used.

I would appreciate a response via mail from anyone who knows the definitive
answer to this question.

				Thank You

				George Swift
				AT&T Bell Labs
				H0 3E-334
				x6105