The Guardian recently offered an explanation of their house style in the matter of capitalization of acronyms etc.

“Use all capitals if an abbreviation is pronounced as the individual letters (an initialism): BBC, CEO, US, VAT, etc; if it is an acronym (pronounced as a word) spell out with initial capital, e.g. Nasa, Nato, Unicef, unless it can be considered to have entered the language as an everyday word, such as awol, laser and, more recently, asbo, pin number and sim card. Note that pdf and plc are lowercase.”

In our world this would mean Bisac yet AAP, Bigny, yet BBGNY (its old name). Of course this is just their house style: nobody’s under any compulsion to follow it. I am certainly not going to update my list of industry acronyms. I now see that this is mistitled, as most of them actually seem to be  “initialisms”, not I confess a word I’d encountered before.

Hart’s rules (Oxford), rather agrees with The Guardian, suggesting that periods should be added “unless the shortened form consists of upper-case initials or is a recognized acronym pronounced as a single word: thus print BBC, HMS, OUP, PAYE, PLC, SDP, SPCK, TUC, WEA; Anzac, Aslib, Fiat, Naafi (or NAAFI).” The option for NAAFI is odd: maybe returning national servicemen were used to seeing it spelled out in all caps, though the “rule” would push in the other direction. I will eschew explanation of this very British list of acronyms.

Cambridge (always more willing to allow the exercise of the educated intellect) allows you to capitalize and punctuate or not as you think best in each work. Consistency and ease of understanding being the (unstated) overriding concerns.