[Jon F. Zeigler]

Yes, the GURPS Fourth Edition TLs are not exactly equivalent to the GURPS Third Edition TLs. In particular, the definitions at TL11+ are a good deal more flexible and setting-dependent.

I intended the following equivalence at higher TLs:

TTL 9 ==> GTL 9
TTL 10-11 ==> GTL 10
TTL 12-13 ==> GTL 11
TTL 14-15 ==> GTL 12
TTL 16+ ==> GTL 13+

Note that at the end of the Interstellar Wars era, the Terrans have entered GTL 11 but have not yet finished it - they don't have jump-4, for example.