how to manage inspire requirements for the use of thesauri in online resource section

these days inspire recommends the use of values from thesauri in inspire registry for multiple elements in online resources. currently the fields in onlineresource panel are hardcoded and it is not possible to introduce these recommended values. I see 3 options to improve this:

• Do not use the online resource panel to add online resources, in stead add online resources inline with full control to define proper field types for the elements
• Use the extension mechanism to redefine the online resource panel to match the inspire expectation
• Use form post processing to update the xml in an automated way in accordance to recommendations

Concretely, INSPIRE recommends to use following thesaurus values in onlineresource section:

• keyword from protocol or mediatype in protocol
• keyword from online description code in description
• keyword from service type for application profile

Protocol has 2 additional challenges

• values need to be selectable from 2 different thesauri (or merge both thesauri to a single)
• geonetwork has hardcoded links between protocol values and certain functionality (add-to-map, etc). Likely the use of this thesaurus will break these links.

Start by reviewing the current online resource panel and the extension mechanism discussed in issue #3720. Compare the existing XML output with the listed INSPIRE thesaurus requirements, then investigate the hardcoded protocol links and determine which of the three proposed approaches can preserve the related functionality.