Known as a 制作委員会, it's a limited liability consortium usually consisting of a broadcaster, production company, animation studio, ad agency, and some otehr companies (like record companies).
In Japan, several companies put together a fund to produce any given animated work.
The one big issue with the Japanese releases of Lain is that they only have the English dub on them, and no English subtitles. Japan and AoA only put 3 or 4 episodes max on a disc, and they use 2-3 times as much video data for each episode. That's why you always see episode splits of 9 and 3 on two discs instead of a 6 and 6 episode spit in US anime releases. All in order to save a few cents by being able to use one BD50 and one BD25 disc for a cour of anime, instead of using two or three BD50 like they should. They cut the bit rates down to a half or third of what Japan uses on their discs, so all that banding and blocking is what you get.
Funi (Sentai too) compresses the hell out of the video in their anime, because they want to be able to shove 8-10 episode on a disc - that's why all their stuff has so much banding and blocking in it.