Section 19.506 style:num-prefix has the text

If the style:num-prefix and style:num-suffix values do not contain any character that has a Unicode category of Nd, Nl, No, Lu, Ll, Lt, Lm or Lo, an [XSLT] format attribute can be created from the OpenDocument attributes by concatenating the values of the style:num-prefix, style:num-format 19.507, and style:num-suffix 19.500 attributes.

The references "style:num-format 19.507" and "style:num-suffix 19.500" are wrong. It should be "style:num-format 19.504" and "style:num-suffix 19.507". But I'm not sure whether to add the section references at all, because section style:num-suffix 19.507 has no references in the similar sentence.