PG2_Unidentified_Record_Types.txt lists:

• record elements that weren't classified during PG2 graphics file parsing, or failed in some way. A text hotspot is attempted on all of these elements.
• GraphicPrimitives that are not interpreted, like polygons, cones, etc.
• drawings excluded from the build based on built in rules or custom edits
• files classified as submodels that are suppressed from being explicitly built
• files which did not meet the criteria for useful graphics and were excluded from the build

This file is now archived in dated error-files folders for diagnostic purposes.