2.1.1 [W3C-RUBY] Section 2.4, The rtc element
The rtc (ruby text container) element serves as the container for rt elements in the case of complex ruby markup. One or two rtc elements may appear inside a ruby element to associate ruby texts with a single base text, represented by an rbc element. More than two rtc elements MUST NOT appear inside a ruby element.
All Document Modes (All Versions)
All rtc elements within ruby elements are displayed.