>The easy solution, if you want to distinguish the 2 and not get them 
>confused with quote glyphs, is found in the Special Characters 
>Palette, not in the 'Arabic' submenu, but under 'Writing', where 
>Left and Right Half Rings appear. Exactly what is needed!

Useful!

>
>Now if I could just remember which is which! I get it right 50% of the time.

The glyph for the ayn resembles its (free standing or left-bound) 
Arabic original in shape, so it is the "left half ring". (Okay, hamza 
also originates in the sign for ayn, but it is smaller, obviously.)

-wp