C3 Innovative elements - approximation table

Specifies for each character in any of the character sets supported (cca 40), how to be represented approximately by fall-back in the target character set, if the character appears to be in the non-exact conversion subset
several alternative representations are specified to take advantage of the different character repertoires of the different character sets

The C3 repertoire

conversion table represented with ASCII
characters represented by their UCS names
other characters of UCS can be indicated with their hexadecimal form in UCS-2 (ISO 10 646-1:1993)

the Common Sub-repertoire consists of 83 invariant graphic characters including SP of ISO 646:1992
the United repertoire of the current version includes 39 coded character sets 7 and 8-bit based, national versions of ISO 646, proprietary character sets and standard character sets which are used in Europe
this includes also 65 control character sets of the C0, C1 and DEL of ISO 8-bit character sets
limited number of additional characters from the European subset of ISO 10 646 - draft ENV of CEN TC304

C0 and C1 sets considered as building blocks of control functions in different contexts
the C3 API is designed to support fully "state full" coded character sets, T.61 (ISO 6937) and ISO 2022
the C3 API is designed to support context-sensitive text