Details of explanation:
"Edit Contents should lay somewhere in between View All Space permissions and Add/Edit Page Permissions on the same space.
In summary User C is a business user whereby User D holds more of a support or junior admin role and should not have the ability to alter the state contents of a page.
In the end, if you have the ability to insert a new Space Permission to the Space Permission grid in Confluence I would suggest inserting Edit Contents with a logical on/off switch between View All and Add Pages. That's assuming third-party vendors are allowed to Add permission switches directly to Space Permissions? If not, then perhaps implying view all also includes edit contents, like where add pages imply edit page as well."
Notes: this might need feedback from other existing users.