What the specification calls for in 3.6.1.11 Addition, that the template
name be replaced with the current repetition index in all attributes of a
block, is not carried out for style attributes and non-CDATA attributes. 

The spec reads: If the template has a name and it is not being ignored (see
the previous two steps), then, for every attribute on the new element, and
for every attribute in every descendant of the new element: if the
attribute starts with a zero-width non-breaking space character (U+FEFF)
then that character is removed from the attribute; otherwise, any
occurrences of a string consisting of an opening square bracket (U+005B,
"[") or a modifier letter half triangular colon (U+02D1, "ˑ"), the
template's name, and a closing square bracket (U+005D, "]") or a middle dot
(U+00B7, "·"), are replaced by the new repetition block's index. This is
performed regardless of the types, names, or namespaces of attributes, and
is done to all descendants, even those inside nested forms, nested
repetition templates, and so forth.

This is related to Opera bug #230280 (?) which is demonstrated at
<http://simon.html5.org/test/webforms2/repetition/addition/001.htm>