Why can't I use the REJECT policy on my iptables OUTPUT chain?

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http://unix.stackexchange.com – I currently have my OUTPUT chain set to DROP. I'd like to change it to REJECT, so that I have a clue that it's my firewall stopping me from getting somewhere rather than a problem with whatever service I'm attempting to access (immediate reject instead of timing out). However, iptables doesn't seem to care for this. If I manually edit my saved rules file and try to restore it, I get iptables-restore v1.4.15: Can't set policy 'REJECT' on 'OUTPUT' line 22: Bad policy name and it refuses to load the rules. If I attempt to set this manually (iptables -P OUTPUT REJECT), I get iptables: Bad policy n (HowTos)