While most content is free and open to the public, a free registration to the IMS/GLC Community enables users to download specification charts and other pdf files. Some material is explicitly aimed to IT professionals, with an overabundance of links.
Plenty of papers, charts and other material is freely available, despite the above limitations for unregistered users. Some content is clearly geared toward IT experts and large corporations
There is an overabundance of links pointing to both internal and external resources. Also a quick link list in each page's left column comes quite handy