Postel's Robustness Principle

Interesting comment from the trenches:

After much testing, it's clear that Postel's advice to protocol designers ("be liberal in what you accept, and conservative in what you send") invites a natural-law repercussion for JS as "protocol":

"If you are liberal in what you accept, others will utterly fail to be conservative in what they send."

Found here: http://mxr.mozilla.org/mozilla-central/source/js/src/jsscan.cpp#1464 while looking at SpiderMonkey source code.