Question: I recognize some of the feature codes, but not others. What is going on?

Answer: You may be familiar with FACC Feature and Attribute Coding Catalog; the GGDM is based on the NSG Feature Data Dictionary (NFDD). NFDD is based on DGIWG DFDD. Some codes are common with FACC, but that is not guaranteed. Even if the code is the same, the concept may actually be different. Do not assume that NFDD is the same just because the code or label is the same. Please look at the definitions to be sure. AGC has a translation for the FACC-based Theater Geospatial Database (TGD) to NFDD-based GGDM.

Question: I am familiar with Point, Area and Line (or Point, Polygon, and Polyline). Why does this documentation not have these common geometries?

Answer: The GGDM follows the NGA convention of Point, Surface and Curve. Some GGDM internal processes still use Point, Area, and Line. Within the Esri GeoDatabase, these are represented as Point, Polygon and Polyline respectively. Feature class names contain geometry designator:
Pnt = Point
Srf = Surface
Crv = Curve
Tbl = Table (non geometric table)
Feature names contain geometry designator :
_P = Pnt
_S = Surface
_C = Curve
Non geometric table names will have _T = Table