I am trying to create a document outlining a work breakdown structure. I would like the first section to be numbered "R3" instead of with the number one, the second section to be numbered "R1" instead of the number two, and the third section to be numbered "SPF" instead of the number three.
Beyond the third section, it would be nice if subsequent sections could be numbered starting from four. Subsections, subsubsections, paragraphs, etc., should have the usual arabic numbering.
For example, the 3rd subsubsection of the 1st subsection of the 2nd section would be: "R1.1.3 Rebuild of the Alu chambers"
Can this be done?
(I know this is the point at which I should share what I have tried, but apart from some fumbling around with \fnsymbol I am entirely lost, and am not even sure what to search for.)