Before an acronym or initialism is used in the text, give the full title or phrase, followed by the shortened form in brackets. After this, use the shortened form only, unless there is a good reason to repeat the full title or phrase in a new section or chapter – for example, if many pages separate the previous use of the shortened form from the next.

As a general rule, if an acronym or initialism would be used just once or twice in the text, write the term in full rather than introducing the shortened form.