On your project page you say:
So this means that my system looks like this.
496 Any old project 10-19 ... 20-29 An interesting area// no project number here 21 A great category// or here 496.21.11 My favourite ID // but check me out!
Within that folder, if I saved an Excel file I would call that file `496.21.11 Whatever descriptive name I’d use.xlsx.
Does that last sentence mean i) you number files and, ii) you do so by giving them the same number as the folder containing them?
496.21.11 Whatever descriptive name I’d use.xlsx exists within
496.21.11 My favourite ID?