TIOBE - C Coding Standard
|Synopsis:||Identifiers shall not use more than the maximum number of characters required for unique identification as specified in the compliance matrix, described in section 1.7.|
|This must not exceed 31.|
Standard C is very restrictive in this area in that in order to support some very old linkers still in use, it specifies a limit of only 6 characters for externally defined names. This almost certainly seriously impacts program readability. The policy of this standard is to require the developer to specify what they used and to ensure statically that this is not exceeded. In general, the developer should use the maximum possible number of characters commensurate with the requirement to maintain unique identification on the platforms defined in the compliance matrix accompanying the application. In practice, this is likely to be considerably in excess of 6 characters.