OpenSSL uses an I/O abstraction called BIO, but nowhere in the documentation I can find does it say what the B stands for (IO is obviously input/output). Various websites suggest that the B stands for basic or buffered, but these are things like blog posts and forum posts without any degree of authority.
Does anyone have an official citation from the documentation, source code, or an OpenSSL developer on exactly what it stands for?
Basic Input Output. According to RSA's BIO SSL Functions description.