To the description of 18.637 table:expression add:
The value of this attribute may have a namespace prefix, followed by the expression. If the namespace prefix is missing it defaults to the "urn:oasis:names:tc:opendocument:xmlns:of:1.2" namespace. If a namespace prefix is present, the expression must start with an '=' equal sign. If no namespace prefix is present, the '=' equal sign may be omitted.
To the description of 18.637 table:expression add:
The value of this attribute may have a namespace prefix, followed by the expression. If the namespace prefix is missing it defaults to the "urn:oasis:names:tc:opendocument:xmlns:of:1.2" namespace. If a namespace prefix is present, the expression must start with an '=' equal sign. If no namespace prefix is present, the '=' equal sign may be omitted.