GPX custom data mapping (Tools=>Options=>Advanced=>Page2)
This option allows you to capture data from a GPX file to populate custom data fields.
Entries in this box are in the format: XmlNode=Custom field name
XmlNode - This must be a list (separated by a ~ )of the matching node names that correspond to the element you want to fetch data for. It must be the full path to the corresponding node.
Custom field name - this is the custom field name in the current database that you want the data updated into. To add custom fields to your database see "Waypoint=>Custom data"
For example, if you added a custom field called Awsomeness and wanted it automatically populated when loading an Opencaching GPX file (from the Garmin site) then you would add the entry:
gpx~wpt~ox:opencaching~ox:ratings~ox:awesomeness=Awesomeness