It WOULD be nice, but such a script step does not exist. Instead you end up with a bunch of If, Else-if, Else Endi If Script steps to produce the same result.
You are welcome to requrest such a new feature if you choose to do so:http://www.filemaker.com/company/contact/feature_request.html
maybe name (via Inspector) all your fields numerically as objects, then loop through them, checking their contents, capturing the field name if it's empty, then using that field name to report it.
Thanx for the replies. I ended up doing the IF then Else Statements. I wasn't able to do the loop cause I have a few layouts that the script has to run on and each of those layouts have slghtly different variables per different layouts. So what I did, and I am sure there is an easier way to do it, but I have a whole whack of IF statements. The start of the script has all the checks that are the same on all the layouts, then I use script parameters to check the fields that are unique to the layout.