signing header required?

[Nicholas Bludworth]

I looked through the FAQ and a few of the archives, but haven't seen 
anything about this. Forgive me if it's a common question. When signing 
a message, is the header at the beginning of the message required? If 
you aren't sure what I am referring to, here it is:

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

I understand that the signature at the bottom is required, but I don't 
understand why the header is needed. On the off chance that it is not 
required, is there a built-in option to turn it off?

thanks for any help-