I don’t know the answer to this question, but I note that the text of the House’s Lobby Disclosure Act, available here for the time being, potentially offers lawmakers a lot of wiggle room for mischief in the way it defines “earmarks.” The bill, which require lawmakers to put their names to the earmarks they sponsor, describes them this way:

For purposes of this section, the term ‘earmark’ means a provision in a bill, joint resolution, or conference report, or language in an accompanying committee report or joint statement of managers, providing a specific amount of discretionary budget authority to a non-Federal entity, if such entity is identified by name. (emphases added)

So if a member of Congess requests, say, $700 million to go towards a grant program adminstered by the Federal Railroad Administration for local rail line relocation and improvement projects, or if a lawmaker inserts a provision granting $230 million to be used by the competent traffic authority in any state whose territory was purchased during the presidential terms of Abraham Lincoln, to connect any island with an airport on it to the mainland, then would such lawmaker have to identify himself?

Further thoughts: It’s not like language even more impenetrable than this doesn’t find its way into federal bills. There’s a tax bill that contains an exemption for companies owned by “a Texas resident whose birthdate is May 16, 1931, and a Michigan resident whose birthday is November 16, 1941.”