Re: Beyond 17 planes, was: Java char and Unicode 3.0+

From: Philippe Verdy (
Date: Thu Oct 16 2003 - 16:20:31 CST

From: "Addison Phillips [wM]" <>

> Here's a proposed solution then. I hereby submit it for use on that
> incredibly distant day in which our oracle fails and a new 1 million code
> point script is added to Unicode (e.g. never).
> When all of the planes less than 16 are full and the possibility of
> exhausting code points become actually apparent (but not before), the UTC
> should reserve a range of code points in plane 16 to serve as "astral low
> surrogates" and another to serve as "astral high surrogates". UTF-16 can
> use a pair of surrogate pairs to address the higher planes thereby
> And we won't all have to muck with our implementations to support this
> stuff.

Too late for plane 16: it's currently assigned to PUAs...
Same thing for plane 15.

But such extension space is certainly available in the special
(spacial? astral? ;-)) plane 14 ...

Which could then be reserved for "hyper-surrogates", referencing
codepoints out of the 17 first planes, and assigned in a open
registry for interchangeable semi-private uses, such as corporate
logographs and other visual trademarks (including the famous
Apple logo character in the MacRoman encoding, or the extra
PUAs needed by Microsoft in its OpenType fonts for Office...)

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