Hello. There's a typo in the doc/diffutils.texi file:
In the example of the Detailed Context node, it reads: *** @var{from-file} @var{from-file-modification-time} --- @var{to-file} @var{to-file-modification time} A "-" is missing in the second line. It should be: --- @var{to-file} @var{to-file-modification-time} Best regards, Mauro.