The <rp> tag is a <ruby> fallback parentheses.
If the browser does not support the <ruby> tag, it will display the text inside this element.
The <rt> element must be enclosed by this element.
An <rp> element with fall-back parentheses. In this Japanese example, if <ruby> is not supported, the parentheses with text is shown, i.e. (Hai).
<ruby>
はい
<rp>(</rp><rt>Hai</rt><rp>)</rp>
</ruby>
rp = ruby parentheses
Here is when <rp> support started for each browser:
 Chrome
|
5.0 | May 2010 |
 Firefox
|
38.0 | May 2015 |
 IE/Edge
|
5.5 | Jul 2000 |
 Opera
|
15.0 | May 2013 |
 Safari
|
5.0 | Jun 2010 |
