Use extended properties to import and export Survey LandXML attributes and to create, assign, and view user-defined attributes.
Using the extended properties command, you can do the following:
To display extended properties, you must specify an sdx_def file that contains definitions, or import a LandXML file with the Create New Definitions Automatically option selected in the Survey Database Settings. By default there are no extended properties defined in the sdx_def file.
Autodesk Civil 3D installs sample sdx_def files at the following location:
C:\ProgramData\Autodesk\C3D <version>\enu\Survey
You can edit default sdx_def files or specify a pre-defined schema with specialized LandXML and user-defined properties contained in an existing sdx_def file. For example, the LandXML - Standard .sdx_def file contains numerous SurveyFeatureClass items. You can open this file in a text editor and make any necessary edits to streamline this file to meet your needs. Use the Save As command and then save the file with a new name.