Does the "usage" notice get printed to stderr?

Question

When the user executes a program with incorrect arguments, and the program prints a 'usage' instruction to the user, should this be printed to stderr?

Answer 1

Many programs do it like this, gcc being one popular example. The rationale is that normal output of the program may be piped out to another program, which will get confused by the error message (which is purely intended for human consumption).