3Di is an ascii file and is organized into sections. The major sections are:
HEADER - contains the file ID and version. This is always the very first entry in the file.
TABLE - multiple tables can be defined. Tables consist of an index number and the property. For example, the NET table would have index numbers followed by a net name. The COLOR table contains index numbers followed by a RGB value.
GEOMETRY - multiple types of geometries. Each geometry can be "tagged" with attributes: direct attributes or attributes drawn from a predefined table. The Table section must appear before GEOMETRY sections that reference table data. Within the GEOMETRY section are different types of geometries.
WIRE_MODELS - this section holds user defined wire models. Note that 3Di holds both the actual geometry of each wire (x,y,z coordinates plus the crossection) and a wire model that was used to generate the coordinates.
DRC_RULES - this section contains a set of DRC rules. The rules can then be run against the geometry by 3DVU's DRC engine. A separate group of geometries holds the error markers generated by the DRC engine.
COMMENTS - are not really a section. They can be inserted anywhere in the file.
