What I'm talking about is a wiki syntax dedicated to explaining command lines. We can all try out best with ASCII art, bullet lists, etc, but what would be perfect would be a format that produces a presentation with roll-over highlights which pop up annotations explaining particular pieces of the command line.
iptables -A INPUT -p tcp --dport 12345 -j REJCET --reject-with icmp-host-unreachableeach part would be explained by a popup.