there is (or at least used to be) at least one investment house that has a deferral source and a catch-up source, for whatever reason, so possibly that is the reason there is a classification of 'catch-up' contributions, even though it makes no sense, because, as noted above, you don't have a catch-up until you hit a limit. but maybe that is what is going on.
ugh, always hated getting a takeover case from that investment house, just the extra work involved, especially if they had loans taken from the sources. always glad to switch the investment house at that point.