Macro content doesn't have a descriptor

We have a descriptor for macro parameters and for the macro itself. An additional descriptor for the content might be useful. It could contain information like:

• is the content mandatory? (same as for any parameter)
• is the content allowed? (some macros might not accept content, like toc macro, and thus the WYSIWYG shouldn't allow the user to edit the content)
• what's the purpose of the content? (we have a macro description but it doesn't necessarily explain what should the user write inside the macro)