Trigger based on multiple fields

To clarify: all the referenced fields are choice fields.

Also, the only other script I've got to work had to be placed in the Table Trigger After Update field. 

Many thanks, Nick.

The following two formulae saved in the Trigger field in PROOFING produce "no" in PROOFING (when the value is selected in WEB STAGE) and nothing at all in the PROOFING STAGE field.

if text('MAG STAGE') = "Ready to proof" or (text('WEB STAGE') = "Ready to proof" or (text('APP STAGE') = "Ready to proof" or text('BEV STAGE') = "Ready to proof")) then
text('PROOF STAGE') = "Ready to proof"
else
null
end

if 'MAG STAGE' = 3 or ('WEB STAGE' = 3 or ('APP STAGE' = 3 or 'BEV STAGE' = 3)) then
'PROOF STAGE' = 2
else
null
end

Have I got the syntax wrong somewhere?

Hum ... it doesn't work on my laptop - or at least it stops me out with a "Formula may not modify data" warning. To answer your question, yes, PROOF STAGE could be a formula field. Sorry to be taking up your Sunday afternoon - and thans for you input!

Ah, brilliant!  Thanks so much - that works great. 

A couple of follow up questions (if you have time).

(1) If I want to do the same thing with a WRITING STAGE field, to alert writers that something's ready to do, how do I add that to the existing script in the table "Trigger after update" field? What goes after "end" to tell Ninox to trigger something else?

(2) How did you manage to put content in the left sidebar of your test file??

Thanks - this is really helpful. 

(1) Oh no, simple as that? Great!

(2) My mistake. I was in table trigger editing mode - Ninox lists the fields in the left sidebar. I just hadn't noticed it before. I meant the sidebar where Find and Calendar sit, but I guess that's not accessible. 

Again, many thanks for your help, Nick.