Perhaps it's confusing to Americans, but it's common among the UK press: > Use all capitals if an abbreviation is pronounced as the individual letters (an init

Perhaps it's confusing to Americans, but it's common among the UK press: > 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, eg 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. https://www.theguardian.com/guardian-observer-style-guide-a https://www.theguardian.com/guardian-observer-style-guide-a It appears they are doing the equivalent of considering pronounced acronyms to be proper nouns. Despite the style ambiguity, it makes a bit of sense if you read the text aloud, as the style gives some indication of how to say the word.