[devidw]

Thanks a lot, clarifying this from the US perspective. Will consider coming up with a less misleading naming.

[gumby]

I actually prefer the US usage, as "parenthesis" is such a lovely metonym that describes the thing it encloses.

People are used to indicating so anyway in speech (referring to a parenthetical remark). And while in writing parentheses can acceptably be set off in a variety of ways, I have a fondness for the good old parenthetical brackets.