ASCIIonly

ASCIIonly is a term describing content that uses only the ASCII character set, i.e., the 128 characters with codes 0 through 127. In practice, this means no accented letters, no non-Latin scripts, no emoji, and no extended symbols.

ASCII was developed in the 1960s as part of early computing standards. Its compact, language-agnostic repertoire made ASCII-only text highly portable across hardware and software, a property that persists in many systems and data interchange scenarios today.

Common contexts for ASCII-only content include source code with ASCII-only identifiers, legacy data interchange protocols such as SMTP, file names on systems with limited character sets, and online services or communities that enforce ASCII-only postings to minimize encoding problems.

Benefits of the approach include easier parsing, fewer encoding issues, and broader compatibility across old software. Limitations include exclusion of many languages and symbols, hindering internationalization and accessibility, and the need for transliteration or back-and-forth escaping when non-ASCII content is unavoidable.

Enforcing ASCII-only constraints typically involves input validation that restricts characters to a safe whitelist, regular expressions, and encoding-aware APIs. When non-ASCII characters are present, teams may replace them with ASCII equivalents, escape them, or migrate to Unicode-based workflows that use UTF-8 internally while presenting ASCII-safe renders at boundaries.

See also: ASCII, Unicode, UTF-8, transliteration, code page.