Plane (Unicode)

Basic Multilingual PlaneSupplementary Multilingual PlaneBMPSupplementary Ideographic PlaneplanesSMPSupplementary Special-purpose PlaneSIPUCS-PUP15UCS-PUP16
In the Unicode standard, a plane is a continuous group of 65,536 (2 16 ) code points.wikipedia
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Unicode

Unicode StandardUnicode Transformation FormatThe Unicode Standard
In the Unicode standard, a plane is a continuous group of 65,536 (2 16 ) code points.
UCS-2 uses two bytes (16 bits) for each character but can only encode the first 65,536 code points, the so-called Basic Multilingual Plane (BMP).

UTF-16

UTF-16BEUTF-16LEsurrogate pair
The limit of 17 planes is due to UTF-16, which can encode 2 20 code points (16 planes) as pairs of words, plus the BMP as a single word. The High Surrogate ( U+D800–U+DBFF ) and Low Surrogate ( U+DC00–U+DFFF ) codes are reserved for encoding non-BMP characters in UTF-16 by using a pair of 16-bit codes: one High Surrogate and one Low Surrogate.
UCS-2 differs from UTF-16 by being a constant length encoding and only capable of encoding characters of BMP.

Code point

codepointcode pointscharacter codes
In the Unicode standard, a plane is a continuous group of 65,536 (2 16 ) code points.
The Unicode code space is divided into seventeen planes (the basic multilingual plane, and 16 supplementary planes), each with 65,536 (= 2 16 ) code points.

UTF-8

65001Unicode (UTF-8)AL32UTF8
. UTF-8 was designed with a much larger limit of 2 31 (2,147,483,648) code points (32,768 planes), and can encode 2 21 (2,097,152) code points (32 planes) even under the current limit of 4 bytes.
Three bytes are needed for characters in the rest of the Basic Multilingual Plane, which contains virtually all characters in common use, including most Chinese, Japanese and Korean characters.

Enclosed Alphanumerics

encircled numbersenclosed alphanumeric
Within the Basic Multilingual Plane, a few additional enclosed numerals are in the Dingbats and the Enclosed CJK Letters and Months blocks.

Unicode block

blockblocksUnicode
Planes are further subdivided into Unicode blocks, which, unlike planes, do not have a fixed size.
Code points not belonging to any of the named blocks, e.g. in the unassigned planes 3–13, have the value block="No_block".

Universal Character Set characters

Unicode characterHigh Private Use Surrogatessurrogate pairs
Of these, 2,048 are surrogates (used to make the pairs in UTF-16), 66 are non-characters, and 137,468 are reserved for private use, leaving 974,530 for public assignment.
The UCS can be divided in various ways, such as by plane, block, character category, or character property.

Specials (Unicode block)

replacement characterSpecialsObject Replacement Character

Halfwidth and Fullwidth Forms (Unicode block)

Halfwidth and Fullwidth Formsfullwidth forms
It is the last of the Basic Multilingual Plane excepting the short Specials block at U+FFF0–FFFF.

Early Dynastic Cuneiform

Early Dynastic Cuneiform (Unicode block)
Early Dynastic Cuneiform is the name of a Unicode block of the Supplementary Multilingual Plane (SMP), at U+12480–U+1254F, introduced in version 8.0 (June 2015).

Private Use Areas

Private Use Areaprivate usePUA
They contain blocks called Supplementary Private Use Area-A (PUA-A) and -B (PUA-B), Private Use Areas, which are available for character assignment by parties outside the ISO and the Unicode Consortium.
Three private use areas are defined: one in the Basic Multilingual Plane, and one each in, and nearly covering, planes 15 and 16 .

Enclosed Alphanumeric Supplement

Enclosed Alphanumeric Supplement (Unicode block)Several enclosed alphanumerics
It is encoded in the range U+1F100–U+1F1FF in the Supplementary Multilingual Plane.

Deseret alphabet

DeseretEnglish (Deseret alphabet)
It also includes English reform orthographies like Shavian and Deseret, and some modern scripts like Osage, Warang Citi, and Adlam.
The Deseret alphabet (U+10400–U+1044F) was added to the Unicode Standard in March 2001 with the release of version 3.1, after a request by John H. Jenkins of Apple, making it one of the first scripts to be added outside of the Basic Multilingual Plane.

Hexadecimal

hex0x16
There are 17 planes, identified by the numbers 0 to 16, which corresponds with the possible values 00–10 16 of the first two positions in six position hexadecimal format (U+hhhhhh).

Word (computer architecture)

wordwordsword size
The limit of 17 planes is due to UTF-16, which can encode 2 20 code points (16 planes) as pairs of words, plus the BMP as a single word.

Byte

bytesBTB
. UTF-8 was designed with a much larger limit of 2 31 (2,147,483,648) code points (32,768 planes), and can encode 2 21 (2,097,152) code points (32 planes) even under the current limit of 4 bytes.

Unicode symbols

symbolsblock
The first plane, plane 0, the Basic Multilingual Plane (BMP) contains characters for almost all modern languages, and a large number of symbols.

Writing

writtentextwrite
A primary objective for the BMP is to support the unification of prior character sets as well as characters for writing.

CJK characters

CJKCJK encodingCJK character
Most of the assigned code points in the BMP are used to encode Chinese, Japanese, and Korean (CJK) characters.

Bit

bitsbinary digitbinary digits
The High Surrogate ( U+D800–U+DBFF ) and Low Surrogate ( U+DC00–U+DFFF ) codes are reserved for encoding non-BMP characters in UTF-16 by using a pair of 16-bit codes: one High Surrogate and one Low Surrogate.