Tagged values in MDriven are metadata extensions that associate additional information with model elements within your application design. They are used to enhance the detail and functionality of your model by embedding extra attributes that can influence how the model is rendered, processed, or interpreted.

Tagged values can store various types of data and configurations that might not be explicitly represented by standard modeling elements. For instance, they are used for storing values as code attributes in generated .NET code, as seen in the example:

[UmlTaggedValue("Kasper.BusinessDeleteValue", "OkEvenIfNotEmpty")] 

This means the tagged value is encapsulated in the model, which influences behavior during runtime or when specific operations are carried out, such as deletion in the given example.

Moreover, tagged values can be utilized widely in aspects such as defining initial values and default database values, configuring UI behavior like hiding headings in groupboxes, or acting as flags for processes within the model-driven development cycle.

Furthermore, the MDriven environment allows users to access, update, and manage these tagged values using tools like the model debugger or via refreshing them from a central wiki resource to ensure that the most current set of configurations is applied. They are an integral part of making the model-driven approach versatile and powerful, allowing developers to incorporate custom logic and constraints without altering the base structural model.

TaggedValue - or Tagged Values/TV - is part of the UML standard.

• It is used as an extension mechanism and is available on all model elements in MDriven.
• It is used by the MDriven Framework for things that are needed but have no definition in UML.
• You can also use it to add additional information on the meta-level of your application.

See also: Tagged value obscurity–remedy

Some important Tagged Values for MDriven Turnkey Web-UI are found here.