href optional in simple links?

I was confused by how the chart in 4.1 of the XLink PR
(http://www.w3.org/TR/xlink/#N1238) shows an "O" for "optional" for the href
attribute in the "simple" column, because the sample DTD in appendix B has
href as #REQUIRED for simple links. I just found the sentence "It is not an
error for a simple-type element to have no locator (href) attribute value"
in section 5.2, so I understand the chart better, but you might want to
change that attribute declaration to #IMPLIED.

Bob DuCharme          www.snee.com/bob           <bob@
snee.com>  "The elements be kind to thee, and make thy
spirits all of comfort!" Anthony and Cleopatra, III ii