• The "edit link" in each <entry> is supposed to have a "rel" attribute value of "edit" [sec. 8.3] but LJ uses "service.edit".
• In "type" attributes it uses the MIME type "application/x.atom+xml", which should be "application/atom+xml" (no "x.").
• The <feed> contains two <link>s whose relations are "service.feed" and "service.post". These aren't part of the current Atom protocol.
These are leftovers from older drafts of the Atom protocol. The "service." prefix in link relations was removed in draft 4, in May 2005. Its presence will confuse Atom clients written to the current spec, rendering them unable to edit or delete existing posts, unless they add special LJ workaround code.
Is the Atom implementation going to be updated to support the current spec?
Or could a modern "rel='edit'" attribute at least be added in parallel to the old one, if the old one has to be kept around for compatibility?