# 27. Ruby Module

This section is normative.

The Ruby Module defines elements for ruby annotation markup as defined in Ruby Annotation [RUBY].

This module adds the ruby element to the Text content set of the Text Module. XHTML 2.0 supports the maximal content model for the `ruby` element, defined as follows:

    ((rb, (rt | (rp, rt, rp))) | (rbc, rtc, rtc?))

As defined in [RUBY], the `ruby` element is not allowed to nest.

Implementation: RELAX NG, DTD