I have an idea for a smaller web app, that I would like to spec out, so others can build it for me. But I cant seem to find an (open source) standard for this?

Snooping around I found an old one that NASA share online: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160011412.pdf - might be a bit overkill. They also share the 2003 version of their engineering handbook: https://www.nasa.gov/sites/default/files/atoms/files/nasa_systems_engineering_handbook_0.pdf - looks cool, but it would be large.

Found this at Stanford: https://uit.stanford.edu/sites/default/files/2017/08/30/Functional%20Specification%20Document%20Template.docx

Is there a good standard one can employ? - or What would you use if you had to specify a smaller project to be developed by a 4-5 man team?

(I'm new to this forum, so apologies for breaking any unwritten (or written) rules).