What ACL Permission provides access to the 'Design' function in editor?

Hi,

Wondering if anyone could point me in the direction of what permission I need to apply to a user group to allow them then access the 'design' function in the page editor? 

I'm a little confused with what permissions control what in AEM and find the guides provided by Adobe just don't do well at clarifying things for me.

If anyone has an actual guide on the specific to what provides what that would be even better

😄

Kindest Regards,