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== [[:wikipedia:UTF-16|UTF-16]] ==

1 or 2 code units of 16 bits = 2 bytes

If 2 code units, first one is in 0xD800-0xDBFF, second one is in 0xDC00-0xDFFF.

* First one: 6 fixed bits (0b110110) then 4 bits encoding the Unicode plan (minus one: 1-16 become 0-15) then 6 first bits from inside the plan - note that the plan number is splitted between the two last bits of the first byte and the two first bits of the second byte
* Second one: 6 fixed bits (0b110111) then 10 last bits from inside the plan

Non-private astral planes 0x10000-0xEFFFF are encoded in UTF-16: [\uD800-\uDAFF\uDB00-\uDB7F][\uDC00-\uDFFF]

Astral planes are encoded in UTF-16: [\uD800-\uDBFF][\uDC00-\uDFFF]

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== [[:wikipedia:UTF-32|UTF-32]] ==

Number of unused bits in UTF-32:

<math>1 - \frac{log_2(17 \times 2^{16})}{log_2(2^{32})} = 1 - \frac{log_2(17) + 16}{32} \approx 0,372266786 \approx 37,2266786 %</math>
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