CWL: Custom data types

Question

[unique_g]

Is there a way (or what is the preferred way) to define custom data types for parameters? Together with allowed values, custom types would enable us to link a parameter interfaced to the end user of a web service running CWL workflows to a suitable frontend component in the service's configuration. In this way, Workflow-specific configuration of the web service could be kept to a minimum, while still offering a high level of flexibility and user experience.