The library was originally only available as part of the Bottom Lines website which is a spanking community site. Just over 900 days ago we made it available outside of BL with its own URL etc. So now most people use the standalone version of the library but a few of the BL members still access it too and they are identified, as you've noticed, with a small icon. If you want to register on BL you can do so at:
http://www.bottomlines.co.uk/