Inkscape’s main unit handling code is in helper/units.cpp and util/units.cpp. The code in helper is originally from libgnomeprint, and the code in util is the start of a rewrite; I plan on moving everything to util. In addition, there is separate code for handling units within an SVG file, for live effects, and for display, as well as a few other miscellaneous header files related to units. Based on these files, I have developed a list of major unit support requirements.

• Listing units
• Handling unit names and abbreviations
• Unit conversion
• Reading units from SVG files

To start, I plan on making the existing code more readable, then moving all unit handling into util/units.cpp, starting with the functions in helper/units.cpp.