C1 controls

The C1 controls are the control characters (code positions 128-159 decimal) which are defined by ISO/IEC 6429:1992 and are part of the ISO 8859 and other encodings. They are not often used, and in otherwise equivalent Microsoft character sets (e.g., Windows 1252) they are replaced by printing characters. It is common in both the web and e-mail for the character set to be announced as an ISO-8859 encoding but actually be in a Windows encoding, including the printable characters where these controls are located in the official standards, making it unsafe for software to even attempt to interpret them as control characters even though that is what the standards technically say to do in such cases. Because of their rarity of use, there is little agreement on their exact meaning and implementation.

Other alternative C1 controls have been used in some applications, such as UK videotex (1982).