For information on the parameters in this dialog that are specific to all formats, see About Writer Feature Types: User Attributes
User attributes are mapped as Feature elements within LandXML. That is, given an arbitrary name-value pair, where such a pair doesn’t match a LandXML element attribute, that element may be used to construct a Feature property label and value.
There are two places where a user may wish to have user-attributes. One is on the feature itself, the other is as a trait on the geometry. How these attributes/traits are handled differs.
In the case of attributes on a feature, only those attributes on the feature which are set on the destination feature-type definitions will be used as LandXML Feature attributes. This allows the user to use the destination feature type to control which attributes are written.
However, because work on geometry traits is currently ongoing, there is no analog to the destination feature type in a workspace. So for user attributes on geometries, all attributes that don’t match a LandXML element attribute will be mapped to Feature property label and value. The exception is that attributes prefixed with landxml_, fme_, and xml_ will not be used as Feature property elements.