Editing Plain text (section)

===Control codes===
{{main|C0 and C1 control codes}}
[[ASCII]] reserves the first 32 codes (numbers 0–31 decimal) for [[control character]]s known as the "C0 set": codes originally intended not to represent printable information, but rather to control devices (such as [[Computer printer|printers]]) that make use of ASCII, or to provide [[Metadata|meta-information]] about data streams such as those stored on magnetic tape. They include common characters like the [[newline]] and the [[tab character]].

In 8-bit character sets such as [[ISO/IEC 8859-1|Latin-1]] and the other [[ISO/IEC 8859|ISO 8859]] sets, the first 32 characters of the "upper half" (128 to 159) are also control codes, known as the "C1 set". They are rarely used directly; when they turn up in documents which are ostensibly in an ISO 8859 encoding, their code positions generally refer instead to the characters at that position in a proprietary, system-specific encoding, such as [[Windows-1252]] or [[Mac OS Roman]], that use the codes to instead provide additional graphic characters.

{{main|Unicode control characters}}

[[Unicode]] defines additional control characters, including [[bi-directional text]] direction override characters (used to explicitly mark right-to-left writing inside left-to-right writing and the other way around) and [[Variant form (Unicode)|variation selectors]] to select alternate forms of [[CJK ideographs]], [[emoji]] and other characters.