Hello all, I've been giving some thought to examining how to re-write siunitx in expl3. I've made some progress on the options side (hence keys3), but I'm now thinking a little about the number analysis part. I wonder if it might be useful to create a lower-level tool package for processing numbers. I was thinking that the following might be useful: - Something like \ifinteger, \ifnumber, etc. as in biblatex - Ability to parse numbers as in siunitx - More structured returning of parsed value The last point is relevant as siunitx uses a number of hacks to get the appropriate data out. I think it might be better to provide something like: <sign><pre-decimal><post-decimal><sign-exp><pre-decimal-exp><post-decimal-exp> or <sign><mantissa><sign><exponent> in a structured return format (errors to be thought about). Does something like this sound useful as a more generalised package? -- Joseph Wright