Currently the only parameter that the "collMod" command can parse is "usePowerOf2Sizes". If you spell "usePowerOf2Sizes" wrong, or put anything else in there, the command still returns

. This is confusing. The command should have better return reporting.

There are different ways to deal with this. I'm in favor of just having the command return

(with an appropriate error message) if you pass in other BSON elements it doesn't know what to do with.