We have been consistently inconsistent with this, historically. The ideal that was agreed a while back was that labels are simple strings with no ".", matching the portion of the term URI after 'schema.org/', while the description (i.e. rdfs:comment) would most properly end with a period / full stop.

This can be checked, roughly, with a SPARQL query. See: http://dydra.com/danbri/schema-org/query#comments-not-ending

SELECT * WHERE { ?p rdfs:comment ?c FILTER regex(str(?c), "[^.]\\s*$") } 

There are some corner cases and details:

• descriptions ending in markup
• descriptions ending with a raw list of URLs (i.e. those from Good Relations where we enumerate external values)

Apart from those, e4a6b88 addresses about 100 easier cases.