My favourite feature of B is that identifiers may contain A to Z, a to z, _ and backspace characters. I presume that they were using printing terminals: teletypes, not video terminals. So an identifier can contain underscored text: you underscore a letter using the sequence letter, backspace, underscore.
An interesting consequence of that is abc^H^H^H___ is a distinct variable from a^H_b^Hc^H_, even though they would look the same on a teletype. Obfuscated coder’s dream!