If you're writing to Geodatabase, some unique attribute types (field types) will be written out as part of the table.
After you generate your initial workspace, click the User Attributes tab on an output feature type. User attributes contain unique data types that you can further define. Most of the attribute types offered are normal attribute types such as char(n), integer, and date; however, domains and subtypes are unique to the geodatabase.
A coded_domain defines a set of values for an attribute in a geodatabase, and consists of a code and its equivalent value. For example, for a road feature class, the numbers 1, 2, and 3 might correspond to three types of road surface: gravel, asphalt, and concrete. Codes are stored in the geodatabase, and corresponding values appear in the attribute table.
A range_domain defines the range of values for a numeric attribute. For example, the permissible range of values for a lot length might be between 70 and 100 feet.
If you uncheck the box and the domain does already exist, the Geodatabase writer will validate the definition of the domain and log a message if the definition in Workbench is different than the definition in the geodatabase (but will not overwrite the existing domain).
Date attributes must be of the form YYYYMMDD, YYYYMMDDHHMMSS, or HHMMSS. If the last format is used, then the YYYYMMDD portion of the date will be set to 19000101.
Subtypes are a subset of features in a feature class or objects in a table that share the same attributes. For example, the features in a vegetation feature class could be categorized into three subtypes: oak, maple, and birch. Creating subtypes can be more efficient than creating many feature classes or tables in a geodatabase.
In the geodatabase, the field must be an integer type in order to be able to create subtypes on it.
For subtypes, descriptions can be supplied as strings, in which case the codes are generated by the Geodatabase writer. For subtype_codes, the input list consists of pairs of codes and corresponding descriptions.
The first code in the list will be used as the default subtype code. If only descriptions are specified, the code created for value1 will be used as the default subtype code. For instance, if you specify subtype_codes 1:a:3:b:4:c:5:d, then 1 (which maps to a) will be used as the default code.