Designing subtypes successfully

The USoft implementation of subtypes has drawbacks when dealing with mandatory subtype columns that have no default value defined for them:

•Do not define Mandatory = Yes for a subtype column unless this is really necessary from a functional point of view.

•Make sure that each subtype column that has Mandatory = Yes also has a default value, if this is at all possible. You can define a default value for a column by setting Default Value at domain level or at column level.

•If you plan to have mandatory subtype columns in multiple subtypes that share the same supertype, be aware that such a construct is relatively difficult to transfer to a different repository when using XML formats (XML.Export, XML.Import, XML.MultiExportTables, as also used by the USoft Delivery Manager XML routines). Special arrangements are necessary. See the Delivery Manager Help for details.

USoft creates a subtype indicator column when you define a subtype. By default, such a subtype indicator is based on the USoft-shipped TW_YESNO domain, this TW_YESNO domain has Default Value = N, and each subtype indicator has Default Value = (null) at column level.

•Avoid subtype indicators with a default value of Y, if at all possible.

•Do not interfere with the TW_YESNO domain and its settings, nor with any other USoft-shipped domain. Use your own domains for columns you define yourself.

•Keep all subtype indicators based on the TW_YESNO domain, if at all possible.