> I would constrain this even further to "Write to stdout only if information is useful as input to another program." No. `foo --help' should never ever write

> I would constrain this even further to "Write to stdout only if information is useful as input to another program." No. `foo --help' should never ever write to STDERR. It breaks piping the message to `less', so I need to either juggle with file descriptors (bash) or use special syntax sugar for this juggling (zsh). Whatever lands in `less', it's hard to be considered "input to another program", because it's mainly message for human that just happens to be paged.