I have a parameter declared with

param name="url.ObjectID" type="numeric" default="0";

My own code-mistake created a link that looked like objects.cfm?ObjectID= (with no value) which rightfully cause an error on the destination page.

There are a half-dozen ways to go about catching this so that it's not reporting user-errors like this to me, but I was thinking that it would be nice to have something like throwmessage, in this case, I would set

param ... throwmessage="ObjectIDs must contain only numbers."

or perhaps param ... throwmessage="ObjectIDs must contain only numbers" type="noreport"

And then in errortrappying, i'd say

writeoutput(e.message); // in this case 'ObjectIDs must contain only numbers'
if (e.type != "noreport")... //log the error

Basically cfparam rolling in cfthrow.