The entire paragraph reads:

"OpenDocument consumers should be able to parse and interpret documents that contain attribute values not defined by the OpenDocument schema. If an attribute which has such a non defined value has a default value, then a conforming consumer should assume that the attribute has this value. Otherwise, a conforming consumer should ignore the attribute."

OK, fix non defined -> non-defined.

But, how does "parse and interpret documents that contain attributes values not defined by the OpenDocument schema" square with:

1) If attribute has a non-defined value, but has a default, use the default value, or

2) Ignore the attribute altogether.

Shouldn't this read:

A conforming consumer that encounters an OpenDocument defined attribute that has a value that is not defined by OpenDocument, then it should:

1) If the attribute has a specified default value, use its default value, or

2) If the attribute does not have a specified default value, ignore the attribute.