José Mejuto wrote:
Hello Lazarus-List,
Thursday, May 5, 2011, 12:20:10 PM, you wrote:
MW> According to unicode.org, when UTF-16 got introduced, the USC2 standard
MW> was extended. So yes they are the same.
MW> In some cases when ppl refer to USC2 they mean the old unicode 1.1
MW> standard, but that is wrong. The name USC2 is misleading and should not
MW> be used anymore.
Maybe, but, taken from www.unicode.org glossary of terms:
UCS-2. ISO/IEC 10646 encoding form: Universal Character Set coded in 2
octets, limited to the Basic Multilingual Plane. (See Appendix C,
Relationship to ISO/IEC 10646.)
UTF-16. A multibyte encoding for text that represents each Unicode
character with 2 or 4 bytes; it is not backward-compatible with ASCII.
It is the internal form of Unicode in many programming languages, such
as Java, C#, and JavaScript, and in many operating systems. More
technically: (1) The UTF-16 encoding form. (2) The UTF-16 encoding
scheme. (3) �Transformation format for 16 planes of Group 00,� defined
in Annex C of ISO/IEC 10646:2003; technically equivalent to the
definitions in the Unicode Standard.
--------------------
I think that the text that says the UCS2 has been extended, does not
means that UCS2 has been extended, it says that UCS2 has been extended
to UTF-16, so UCS2 can not be considered Unicode anymore as noted in
ISO 10646:
UCS-2. UCS-2 stands for �Universal Character Set coded in 2 octets� and is also
known as
�the two-octet BMP form.� It was documented in earlier editions of 10646 as the
two-octet
(16-bit) encoding consisting only of code positions for plane zero, the Basic
Multilingual
Plane. This documentation has been removed from ISO/IEC 10646:2011, and the term
UCS-2 should now be considered obsolete. It no longer refers to an encoding
form in either
10646 or the Unicode Standard.
From the basic FAQ:
Q: What is the difference between UCS-2 and UTF-16?
A: UCS-2 is obsolete terminology which refers to a Unicode
implementation up to Unicode 1.1, before surrogate code points and
UTF-16 were added to Version 2.0 of the standard. This term should now
be avoided.
UCS-2 does not define a distinct data format, because UTF-16 and UCS-2
are identical for purposes of data exchange. Both are 16-bit, and have
exactly the same code unit representation.
Sometimes in the past an implementation has been labeled "UCS-2" to
indicate that it does not support supplementary characters and doesn't
interpret pairs of surrogate code points as characters. Such an
implementation would not handle processing of character properties, code
point boundaries, collation, etc. for supplementary characters. [AF]
from the "Both are 16-bit, and have exactly the same code unit
representation" I concluded they are the same
Anyway, we're drifting away from the original question.
Marc
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