in reply to The Definitive Unit Conversion Script
Perhaps more importantly, there's some unit conversion modules already out there that might bear further scrutiny:
Of these, the Convert-Units bundle seems to be on the money, since in the author's words:
It is intentionally distinct from the Math::Units module. Why? The Math::Units module implies that unit conversions are exact, with one-to-one relationships. This is fine for scientific work. It's even fine for some general purpose/real-world uses (such as converting Fehrenheight to Celcius).
Real-world measurement systems are conflicting. For instance, a "point" in typography is equivalent to 1/72 inch, according to PostScript specs and common usage. Other type systems consider it 1/72.27 inch, or 0.01383 inches, or 0.0148 inches. Outside of that context, a point may be 1/120 or 1/144 inch.
Common notations and abbreviations also depend on context. Does "12 pt" mean "12 point", "12 parts" or "12 pints"?
Even without conflicts in the definition of a particular unit, there's no need to convert point sizes for fonts into miles or light-years. Typesetters, surveyors and astronomers user different scales as well as systems.
Hope these are of assistance. At the very least, you can mine the modules for conversion tables!