Note I:
the exclamation-mark, it should be displayed as the last (not first) character,
this is a good way telling if the content is text aligned to the right.
Note II:
A little confusing but it seems that in GitHub,
dir="RTL" is equal to CSS' text-align:right;, (inner-text is rendered from right-to-left)
while align="right" is equal to CSS' direction:rtl;, (container is rendered from the right-side)
Note III: