GNU bug report logs - #15074
24.3; Possible typo in the Elisp Reference Manual - section 2.3.3.4

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From: Eli Zaretskii <eliz <at> gnu.org>
To: Sian Mountbatten <poenikatu <at> fastmail.co.uk>
Cc: 15074 <at> debbugs.gnu.org
Subject: bug#15074: 24.3; Possible typo in the Elisp Reference Manual - section 2.3.3.4
Date: Mon, 12 Aug 2013 14:38:08 +0300

> Date: Mon, 12 Aug 2013 09:38:57 +0100
> From: Sian Mountbatten <poenikatu <at> fastmail.co.uk>
> 
> In section 2.3.3.4 of the Elisp Reference Manual, this sentence occurs:
>     The integer that represents such a character has the $2^{27}$ bit
>     set.
> 
> I have expressed the number using the TeX/LaTeX manner. The
> point is that, in the following paragraph, the text refers to the
> $2^7$ bit. I suspect, therefore, that the 27 mentioned should really
> be 7.

No, it's not a typo: the META modifier bit of a character is indeed
0x8000000.

> If 27 was intended, that would mean that char tables would have
> to accommodate more than 134 million characters! Surely not!

As a matter of fact, char tables can accommodate all the Unicode
character space, but they do that in an efficient way, not by
allocating a flat array.  Nevertheless, the META bit is unrelated to
the capacity of a char table, since modifiers are not stored there.

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