Editing UTF-8 (section)

=== Surrogates ===
Since RFC 3629 (November&nbsp;2003), the high and low surrogates used by [[UTF-16]] ({{tt|U+D800}} through {{tt|U+DFFF}}) are not legal Unicode values, and their UTF-8 encodings must be treated as an invalid byte sequence.<ref name="rfc3629"/> These encodings all start with {{tt|0xED}} followed by {{tt|0xA0}} or higher. This rule is often ignored as surrogates are allowed in Windows filenames and this means there must be a way to store them in a string.<ref name="PEP 529">{{ cite web | title = Change Windows filesystem encoding to UTF-8 | id = PEP&nbsp;529 | website = Python.org   |language = en | url = https://www.python.org/dev/peps/pep-0529/ | access-date = 2022-05-10 }}</ref> UTF-8 that allows these surrogate halves has been (informally) called ''{{visible anchor|WTF-8}}'',<ref name="wtf-8">{{cite web | title = The WTF-8 encoding | url = https://simonsapin.github.io/wtf-8/}}</ref> while another variation that also encodes all non-BMP characters as two surrogates (6&nbsp;bytes instead of 4) is called ''[[CESU-8]]''.