There are a few similar types of connectors: BLS, BLD, HU, PHU. They are frequently encountered in electronic devices, but I couldn't find any information on them. Google only finds a bunch of places to buy them, sometimes with a picture and a short description. Where can I find more information? What do their names stand for? What company invented them, and when? Where is any documentation, specifications, or other documents? What other similar types of connectors exist? Why does any information on these connector types seem to be completely absent from Wikipedia and other informative websites?
Here are some images: