The grammars are called slot grammars because they are organized around slots (grammatical relations) and rules for filling them. The parser works bottom-up and maintains, for each phrase being built up, a list called the available slots list, ASLOTS.

777 is used on most slot machines in the United States to identify a jackpot. As it is considered a lucky number, banknotes with a serial number containing 777 tend to be valued by collectors and numismatists. The US Mint and the Bureau of Engraving and Printing sells uncirculated 777 $1 bills for this reason.