Modula-2 source text is encoded in 7-bit ASCII or UTF-8 encodings and all compilers on all platforms must at minimum recognise 7-bit ASCII and UTF-8 encoded source text regardless of the actual character set used on the platform.
In addition to the required encodings, compilers may support other Unicode encoding schemes natively.
Modula-2 development systems hosted on EBCDIC based computer systems without ASCII or UTF-8 support are required to provide a transliteration utility which must be external to the compiler and convert between EBCDIC and 7-bit ASCII or UTF-8 encoded source text. At minimum, the EBCDIC500 encoding shall be supported by any such transliteration utility.
In the now unlikely event that a Modula-2 development system is to be hosted on a 6-bit character set based platform without ASCII or UTF-8 support, the system is required to provide a transliteration utility which must be external to the compiler and convert between digraph or trigraph encoded 6-bit representation and 7-bit ASCII encoded source text.
Implementors of transliteration utilities may choose whichever digraph or trigraph transliterations they see fit provided that the transliterations are reversible. However, it is safest to follow the transliteration recommendations as their digraphs have been reserved.