Hi, Gabriel
What you seem to need is the (afaik) still unexisting port of Products.ATVocabularyManager to Dexterity. There's an option but I'm not sure it'd fit your usecase (I didn't try it):
- http://bo.geekworld.dk/introducing-collective-taxonomy/
- https://pypi.python.org/pypi/collective.taxonomy
A simpler version would be creating a Site Setup configlet to store the professions with a simple textarea or a more complex custom widget. You could provide easy access to selected users using group portlets. See (but avoid the Grok approach):
I don't think the professions are going to be updated very often, are they? All site users will be able to update them or just a selected few?