Mandatory <sch:properties> element in Schematron 2016?

Hello all,

The RELAX NG schema for Schematron in Annex A of Schematron 2016 makes
the sch:properties element mandatory.

,----
| schema = element schema {
|   attribute id { xsd:ID }?,
|   rich,
|   attribute schemaVersion { non-empty-string }?,
|   attribute defaultPhase { xsd:IDREF }?,
|   attribute queryBinding { non-empty-string }?,
|   (foreign
|   & inclusion*
|   & (title?, ns*, p*, let*, phase*, pattern+, p*, diagnostics?, properties))
| }
`----

The introduction on the other hand states that the 2016 edition is
backwards compatible with the Schematron 2006.

Is this an error in the schema provided in Annex A?

All the best,
  -- David

-- 
David Maus M.A.

Mobile: +49-151-61506713
Www: http://dmaus.name