Thanks to a lot pf help from Phil and Bruce here (and in other places), I've now got a number of scripts working perfectly which extend, constrain and generally do wonders with checkboxes (and other text fields).
The final remaining thing which I want to do is error-check for an absence of any Find criteria at all.
But the result, Error Code 400, only applies to the most recent Result.
In the case of my script - which progressively Extends and Constrains Found Sets, rather than Performing a single Find - it may well be that there really is no value for that actual very last field which was checked with:
Is there a preferred way to determine whether every field in the Find operation really is empty; or do I have to script a series of flags (each based on the Last Error Code received)?