Howdy, Lenard,
There are static (shared) collections that contain the database types and field lengths for the business objects. Each business object class has it's own set of collections. Being static, you cannot access them through the "this" (or Me) reference, you have to use the ClassName.Collection notation.
If you look in one of the .designer.* files for your business objects and go to the static constructor for the class, you'll find where the collections are populated the first time a business object of that type is created.
AllFieldsList -- A List<string> containing all of the fields in the business object
FieldDbTypes -- A Dictionary<string, System.Data.DbType> containing the DbTypes of all of the fields on the business object
FieldEnums -- A dictionary containing the enum values that represent each field. You can also obtain the values by using Enum.Parse(), but it's faster to pull them from a dictionary
FieldLengths -- A Dictionary<string, int> containing the lengths of the fields
FieldNativeDbTypes -- A Dictionary<string, int> containing the native DbType enum values for the business object. If the BO was mapped to a SQL database, then the values will be System.Data.SqlDbType and can be cast accordingly. System.Data.OracleClient.OracleType for an Oracle BO, System.Data.OleDb.OleDbType for OLE DB, etc.
Hopefully that will help.