Best way to throw custom error from SubVI

Question

Hi
I was wondering how best to throw error messages from a SubVI.
Say I have a toplvl VI called Caller.vi which calls Sub.vi. The toplvl vi whishes to use the Sub.vi's error out cluster to determine what to do - e.g. halt execution of the toplvl vi if the Sub.vi throws an error. Easy enough if the Sub.vi just have to pass errors from build in LabView functions and VI's, but how to do it if the sub vi has to throw a custom error upon some condition?
Say the sub vi takes a certain number of inputs and that the inputs need validation before executing what ever the sub vi does. E.g. a certain algorithm implemented is only meaningfull if a>10.
My own thought is this: Simply select between an empty/no-error error cluster and an error-cluster containing the wanted custom errorcode and description. The area circled in blue is the interesting part:
Is that the worst idea you've iever seen implemented?
The only other real suggestion I've been able to find (which originally adresses another issue, but shows a method for "throwing an error") is a VI posted in this thread: http://forums.ni.com/t5/LabVIEW/Throw-an-error/m-p​/882575 which looks like:
Please help me out guys How to throw a custom error which is not intended for the end-user, but intended to ease the life of a develper calling the sub-vi if he/she wishes to.
Best regards
Wuhtzu

Answer 1

Thank you tbob. (EDIT: and thank you blawson)
I know all about volunteering and having jobs to do - I participate in quite a few fora. I just thought that my topic was lost since after only 2 days it was on page 3 of the forum - but if page 3 isn't forgotten I will remember that next time and also if 2 days isn't patient I will also remember that
To you answer: The error code should be negative, shouldn't it? Even though an indicator wired to error-out of a build in labview function will actually display error codes as positive... maybe it's diffrent form labview version to labview version. My v2010 manual reads:
"You can define custom error codes in the range of -8999 through -8000, 5000 through 9999 or 500,000 through 599,999"
So say I want to throw an error with error code 5687 - should I then wire -5687 or +5687 to the cluster?
Thanks - Wuhtzu