I am wondering how I can set permissions on a field for a specific group ideally through python or xml as it is a custom module. I have a field 'assigned_users' that I need one group to be able to change and write to but for the other group it should be read only. I can't use the group visibility as it still needs to be visible to everyone, just not writable. This could be done by either granting write only to the one group or restricting to read only for the second group, I am just unsure of how this is actually achieved.
Many thanks.