Thanks for the pointer to the running total example; I think it will help a lot (somehow my site searching on earlier visits around "math" did not get me to locate this page but I was perhaps not specific enough on my search terms!)
Also thanks for the guidance on the calc exclusions from entry on the db side; I had mainly included these there for the time being in order to monitor the effects of my experimentation with the modelling within the MySql table to comprehend how my modelling tweaks changed outcomes. Your recommendation to use diplay fields will however be the more appropriate construction for the final.
I hope to carve out some time at the weekend to work through your other modelling comments you offer with the model alongside to see if I can crack this. Once again, thank you for the effort and follow-up that you invest to support this very fine program; its much appreciated.
Kind regards, Al
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