Re: [Json] Proposal for strings/Unicode text

[John Cowan <[e-mail]>]

Norbert Lindenberg scripsit:

> JSON syntax allows almost all Unicode code points (with the exceptions
> visible in the "unescaped" production) to be inserted into strings
> directly, so escape sequences are mostly a convenience for using JSON
> in environments that restrict the set of allowed characters (such as
> RFCs), don't have the necessary fonts and input methods installed,
> or benefit from making the code points visible (e.g., in test cases).

Officially, yes.  But surrogate code points cannot be inserted directly
if the representation is UTF-8 (otherwise it becomes CESU-8 instead)
or UTF-16 (otherwise it is broken UTF-16) or random non-Unicode encodings.
So UTF-32 is the only encoding into which a surrogate code point can be
inserted directly -- and nobody uses it.

In practice, therefore, code points in the range D800-DFFF must be escaped
if they are to be used.

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