The first thing we did to create the master SVG was open Inkscape and create a new US Letter size document. To keep things organized, we created four layers in the new document: scan, overlay, ...

The SVG standard does not include layers, but it does include groups and Inkscape layers are simply SVG groups with some extra Inkscape-specific parameters attached.

Inkscape also supports Creative Commons metadata, node editing, layers, complex path operations, bitmap tracing, path-based texts, circumfluent object text, direct XML editing and much more.