Features read from a database consist of a series of attribute values. They have no geometry.
The attribute names are as defined in the DEF line if the first form of the DEF line was used. If the second form of the DEF line was used, then the attribute names are as they are returned by the query, and as such may have their original table names as qualifiers.
The feature type of each Microsoft SQL Server feature is as defined on its DEF line.
Features written to the database have the destination table as their feature type, and attributes as defined on the DEF line.