The quote event has the NBBO ask/bid sizes. According to the CTA/UTP specifications, the ask/bid sizes in the raw quote messages are represented in round lots.
Apparently, the round lot size can vary depending on the security. The UTP quote message has a “Round Lot Size” field to determine how many shares are in one round lot for the given security. I assume CTA has something similar.
Does Alpaca convert the ask/bid sizes from round lots to individual shares before returning them in the Alpaca quote event? If not, does Alpaca provide the round lot size somewhere? Otherwise, the ask/bid sizes cannot be relied upon.