CHAT: Cool Mac Unicode

I've just discovered that, with the keyboard on my Mac set to US Extended
(Unicode), whenever I enter the key combination for the macron (Alt + a) and
press "r" or "l" next, a dot is automatically added underneath, which I
presume corresponds to the IPA syllabicity symbol, or the Sanskrit
romanisation for vocalic "r"s and "l"s. Which I thought was really cool and
that I'd share. Interestingly, the only non-vowel letters that can take the
macron are "s", "r" and "l". But "s" doesn't get the subscript dot (nor of
course, do the vowel letters).
Cheers,
Eugene