The bottom line up front, I agree with. But I'm not sure why I would use giant ACTION KEYWORDS like "DECISION" or "COORD" in any of my subject lines, ever.

Why would you want to lend a cold, impersonal, robotic tone to your email?

I find it more effective to just write a concise subject in the form of a question. Include the question mark. No caps. If it hasn't been responded to, perhaps resend with "(second attempt)" at the beginning of the subject.