U.S. DEPARTMENT OF THE INTERIORBUREAU OF LAND MANAGEMENT
GIS Downloadable Data
Downloadable data is now available at http://www.blm.gov/ca/gis/index.html
BLM Data Naming Rules
The Three-letter theme codes are part of the standard coverage naming convention used in California. This naming convention was established to help facilitate the limited coverage name length in arc/info (max 13 characters) and establish some type of standards to identifying the contents of our single-theme-based coverages.
The naming convention is as follows:
The data type contained in this coverage. Valid data types are:
The geographic extent of data. Geographic extent can be represented by the state (ca), field office name/code (cdd, 060), optional code designated by the Field Office, or one of the standard California map naming convention codes used to identify a quad location and scale. Generally this code would include a two digit latitude, a three digit longitude (drop the "_" sign), and at the end, the two character code from the USGS "Ohio Convention"
11 = optional characters used to further identify the coverage