ASCII
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... The rules for formatting and submitting an RFC are defined in [5].
Every RFC is available in ASCII text. Some RFCs are also available
in other formats. The other versions of an RFC may contain material
...
... in other formats. The other versions of an RFC may contain material
(such as diagrams and figures) that is not present in the ASCII
version, and it may be formatted differently.
...
... requirement applies to standards-track *
* specifications: the ASCII text version is the *
* definitive reference, and therefore it must be a *
...
... incorporate by reference the ANSI standard character set "ASCII" [2].
Whenever possible, the referenced specification shall be available
...
... ASCII ...