Clarify rights owner

Author: niemela

spec/2023-07-draft.md

@@ -151,7 +151,7 @@ Key                                               | Type
 [credits](#credits)                               | String or map with keys as defined below      | No        |
 [source](#source)                                 | String, a sequence, or a map as defined below | No        |
 [license](#license)                               | String                                        | No        | `unknown`
-[rights_owner](#license)                          | String                                        | See below | See below
+[rights_owner](#rights-owner)                     | String                                        | See below | See below
 [embargo-until](#problem-publication-embargo)     | Date                                          | No        |
 [limits](#limits)                                 | Map with keys as defined below                | No        | See below
 [keywords](#keywords)                             | Sequence of strings                           | No        |
@@ -310,9 +310,12 @@ Value           | Comments
 `educational`   | May be freely used for educational purposes.                                       |
 `permission`    | Used with permission. The rights owner must be contacted for every additional use. |
 
-`rights_owner` is the owner of the copyright of the problem.
-Values other than `unknown` or `public domain` require `rights_owner` to have a value.
-`rights_owner` defaults to `credits.authors`, if present, otherwise value of `source`.
+### Rights Owner
+
+A rights owner is needed if the [license](#license) is anything other than `unknown` or `public domain`.
+If `rights_owner` is provided, this is the rights owner.
+Otherwise, if one or several authors are specified in `credits`, that group or individual is the rights owner.
+Otherwise, if a `source` is specified, the legal entity owning the rights associated with that source is the rights owner. 
 
 ### Problem Publication Embargo