7BitASCII

7BitASCII is a term used to describe the 7-bit subset of the ASCII character encoding, intended for systems and channels that transport data as 7-bit units. In practice it corresponds to the standard ASCII character set defined for 7-bit bytes, with 0 through 127 available for control and printable characters. The concept arose in early computer networks and telecommunication protocols that could not reliably transmit 8-bit data, such as some email transports and line-oriented interfaces.

Character set: The 128-code set includes control characters in the range 0–31 and 127, and printable characters from 32 to 126. The printable characters comprise the space, digits, punctuation marks, and the basic Latin letters (A–Z, a–z). There are no accented characters or non-Latin symbols in the base 7BitASCII set.

Usage and compatibility: 7BitASCII is effectively the same as the generic ASCII standard; the qualifier emphasizes that data should remain within 7-bit boundaries. When data may contain 8-bit bytes, it is typically encoded for transport using 7-bit safe encodings (for example quoted-printable or base64) to preserve compatibility with 7-bit channels.

Limitations and modern context: 7BitASCII does not include extended ASCII or Unicode characters, limiting its usefulness for international text. Modern systems generally adopt Unicode encodings (such as UTF-8) and separate normalization and encoding schemes for interoperability; however, legacy protocols and systems continue to reference 7BitASCII as a baseline for ASCII compatibility. Related topics include ASCII, UTF-8, 8-bit ASCII, and base64.