5.2 \version in documentation files

Every documentation file which includes LilyPond code must begin with a \version statement, since the build procedure explicitly tests for its presence and will not continue otherwise. The \version statement should reference a version of LilyPond consistent with the syntax of the contained code.

Since the \version statement is not valid Texinfo input it must be commented out like this:

@c \version "2.19.1"

So, if you are adding LilyPond code which is not consistent with the current version header, you should

1. run convert-ly on the file using the latest version of LilyPond (which should, if everybody has done proper maintenance, not change anything);
2. add the new code;
3. modify the version number to match the new code.