By all accounts, pledges to the 2013 Combined Federal Campaign are going to be down by tens of millions of dollars in comparison with the 2012 CFC. This is, of course, money that mostly goes to charities. But which charities benefit from federal employee giving (and could thus see a falloff in contributions)? The Office of Personnel Management does not collect that information. Instead, the Workplace Giving Alliance, a Massachusetts-based coalition of CFC federations, decided to do the job on its own, compiling pledge information for the last three years from most local campaigns and then extrapolating to fill in…