2.1.1 [W3C-RUBY] Section 2.4, The rtc element
The specification states:
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.