[ic] Is there one place to define meta_header for all pages?

[Kyle Kirkland]

I've noticed that in all of the templates they're accessing
a variable named "meta_header" ([scratchd meta_header]) which
doesn't seem to be set anywhere.  I'd like to utilize this
variable to setup the <META> tags on my site so I don't have
to duplicate the same tags on every page.

Should I define the variable in each template, or is there a
single file I can modify to maintain my <META> tags?