I am writing a paper about a super machine (SM). In the introduction section I am briefly introducing the concept and also the acronym. Then, later in the text, I have a full section which explains SM in detail.
Should I spell out SM in this section's title or write it out? It seems strange if the title of the section is just "SM" instead of "Super machine". Further, given the importance of this section for the whole puplication, should I re-introduce the acronym SM the first time in this section, even though the acronym has already been introduced in the introduction?