One of the cardinal rules of writing is explaining acronyms. Acronyms are abbreviations of a string of words, commonly using the first letter of each significant word in the text string. Acronyms are useful and abundant in technical jargon.
I lost count how many times I have read an online tutorial or forum reply only to pause and hunt the meaning of an acronym.
Some people argue that many acronyms do not need to be explained. Or that a person familiar with a topic will know. These arguments ignore new users and people who are not subject matter experts.
The format to use an acronym is simple. The first time an acronym is used type the full text string and before ending the sentence add the acronym in parentheses. For example,
Submit an Engineering Change Notice (ECN).
From that point forward in the text using only the acronym is acceptable.
In lengthy documents such as technical or reference manuals, often the rule is repeated for each chapter.