It is as Bluewizard says:

Name: Maemo Extras-devel
Web Address: http://repository.maemo.org/extras-devel
Distribution: fremantle
Components: free non-free

Im not sure if its case-sensitive, but I wouldnt be surprised, asi this is Linux ... (so, use fremantle instead of Fremantle). On the other hand, Im sure distro is fremantle, not fremantle-1.2 ...

EDIT: Yeah, after some thinking Im sure its case-sensitive, as its supposed to be a web adress pointing at files on a server after all ...