When configuring properties for an external entity in Subversion there is the option to refer to the entity with peg or operative revision number.
For example when including "bar" within repository "foo", found on the same server as our current working copy, we can use one of these definitions:
^/foo/bar@123 bar # peg revision
-r 123 ^/foo/bar bar # operative revision
I understand the difference between peg and operative revisions in general. Which syntax would be the preferred one when defining an external in Subversion?