GMM Township Records

TPC can import GMM Township Record files. These generally have a .RAW extension, and contain record data for a township.

Importing a GMM Township File

Using a Coordinate Reference System

If possible, TPC will base the township computations on a CRS (Coordinate Reference System). This allows it to do PLSS computations with the record data.

TPC first checks the current survey for a valid CRS. If one is found, it is used. If one is not found, TPC prompts you to select one and uses the one you select. If you do not select a CRS, TPC tells you that it will continue to import the GMM file, but all computations will be based on grid.

If TPC is able to continue with a valid CRS, it will check each imported point from the GMM file for an existing point in the survey. The first match will be used to locate the township on the survey's CRS. If no matching points are found, TPC will compute the township at the center of the survey's CRS and will display a message telling you so.

Using the imported data

TPC creates a traverse named 'Record T[township] R[range] [principal meridian] ' by reading the township, range and meridian values from the file. This traverse contains the record data from the file.

Because the traverse name includes the word 'Record', TPC knows that it holds record data and will use the data in the traverse to provide record data to lost corner routines like the  Single and Double proportion dialogs.

Plotting the Township

As TPC imports the GCDB township records, it creates a traverse that can be used to plot the township. TPC inserts a Gap between each tier imported.

To plot the township, tag the imported traverse in the Traverses Manager.

Note: township records are imported without coordinate positions. You will probably want to translate the township to a reasonable position within the CRS to get the expected convergence in the plotted township.

Appending an 'R' to Imported Point Labels

By default, TPC appends the letter 'R' to the point labels imported from this file. This is to distinguish GCDB 'Record' data from 'Retrace (measured)' data.

This option can be turn On or Off in the GMM Township Records Settings dialog.

SID Values

The Source IDs (SIDs) read from the file can be appended to the point descriptions. TPC does not look for, or read, the related Z-file (.SID).

This option can be turn On or Off in the GMM Township Records Settings dialog. The default is On.


Geographic Coordinate Data Base, User's Guide, BLM, Oregon State Office

Related Topics

Importing Data
Exporting Data