Here are the original code descriptions: (Answered my own question)
Code Code Description a acquisition b bunched trade - average price c cash trade d distribution e automatic execution f intermarket sweep g bunched sold trade - opening/reopening trade detail h intraday trade detail i basket index on close transaction j rule 127 trade k rule 155 trade l sold last n next day o opened p prior reference price r seller s split trade t form t trade - pre/post market trade u extended hours traded - reported late or out of sequence w average price trade y yellow flagged regular trade z sold - out of sequence