Limit the allowed characters in attribute names

After discussion here: beetbox/beets#3758 (comment)
beetbox · Mar 7, 2021 · 9c94ac5 · 9c94ac5
1 parent 3b45b22
commit 9c94ac5
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/docs/api.rst b/docs/api.rst
@@ -111,6 +111,8 @@ fields not listed in this specification. The optional fields are included in
 an effort to standardize the name and format of common (albeit not universal)
 metadata.
 
+Names of attributes, including non-standard attributes, **SHOULD** only contain
+characters matched by the regular expression ``[a-zA-Z0-9_-]``.
 
 .. _relationships: