dependency in fields
Accepted answer
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Please see https://jazz.net/library/article/1093 Lab 4 and the hinted links about what is available out of the box today. The workshop part covering JavaScript should be published soon too. JavaScript could add a bit more flexibility.
Please be aware, that workitem customization and JavaScript are limited today and it might be possible that your request can not be solved using them today. It is possible to code value provides as extension to the Eclipse and the Web UI, but it is quite complex. In contrast, it is easier to create a Server pre-condition, that prevents saving wrong combinations. So if you can't use customization or scripting, I would suggest looking into preconditions.
Please be aware, that workitem customization and JavaScript are limited today and it might be possible that your request can not be solved using them today. It is possible to code value provides as extension to the Eclipse and the Web UI, but it is quite complex. In contrast, it is easier to create a Server pre-condition, that prevents saving wrong combinations. So if you can't use customization or scripting, I would suggest looking into preconditions.