The E00 reader provides complete support for reading ArcInfo regions, while the E00 writer currently has a very limited form of support for writing ArcInfo regions. An ArcInfo region is essentially a set of non-overlapping polygons with a logical connection. They are represented in the RPL and RXP subfiles, and their attributes are defined in the .PAT<subclass> info files.
The RPL file is virtually identical in structure to the PAL file. It defines the polygons which make up the various regions by listing the arcs that make up the polygons’ boundary and holes. The only real difference in structure between the PAL and the RPL is that regions may be divided into subclasses, so the contents of the RPL file are likewise divided into subclasses, with all polygons belonging to regions of a single subclass appearing together within the RPL file.
The RXP file defines the actual regions by cross-referencing the polygons defined in the RPL file with region IDs. Each data line of the RXP file contains a region ID and an RPL polygon ID. The records of the RXP file are grouped by subclass.
Regions’ attributes are stored in info files named <baseName>.PAT<subclass>, much as the text attributes are stored in <baseName>.PAT<subclass>. The records of the region attribute tables contain <baseName>-ID attribute that relates them to the regions defined in the RXP file.
Workspaces generated by FME to read E00 will fully recreate complete regions and output them as area features.
To write regions out to an E00 file, the workspace must define FME features that represent the RPL, RXP, and .PAT<subclass> records as they are to appear in the output file. This means that the every aspect of the regions, from the topology down to the assignment of IDs, and the ordering of the records with each subfile, must be performed in the workspace; the E00 writer will simply write out whatever information it is given.