ISO 646 (freely available as ECMA-6) defines a framework for 7-bit Latin encodings with 12 undefined positions available for standardisation by national bodies according to local needs (PDF, ref. ISO-IR 170).

A large number of national variants have been in use. The ones mentioned below still enjoy support in Internet Explorer (as of version 9.0).

ISO 646-IRV (International Reference Variant)

x-ia5

252 2 + 1

PDF. Ref.: ISO-IR 2.

This version is deprecated; the current official International Reference Variant is identical to ASCII.

The IE implementation substitutes ‘∇’ (U+2007) for the delete character (U+7F).

ISO 646-US (ASCII)

us-ascii

253 2

PDF. Refs: ISO-IR 6, ANSI X3.4.

ISO 646-DE (German)

x-ia5-german

253 2

PDF. Refs: ISO-IR 21, DIN 66003.

ISO 646-NO2 (Norwegian, version 2)

x-ia5-norwegian

253 2

PDF. Refs: ISO-IR 61, NS 4551.

ISO 646-SE2 (Swedish, version 2)

x-ia5-swedish

253 2

PDF. Refs: ISO-IR 11, SEN 85 02 00.