SDC feature class

[ESRI software] A highly compressed, read-only data structure that can store spatial geometry (points, lines, and polygons), and attribute data. The SDC structure supports geocoding, routing, and most spatial operations. SDC is the core data structure used in ArcGIS StreetMap, ArcIMS RouteServer, RouteMAP IMS, ArcGIS Business Analyst, and BusinessMAP.