Many thanks...I'll study your post in detail tonight (after I've got the kids off to bed!)

I wasn't expecting anyone to analyse my code - I only offered it up in case someone wants to get an overall vibe for my approach. Equally, I wouldn't want anyone to write it for me (else I'll never learn) - I seek exactly what you've brought to the table....ideas wrt general approach from those that have trodden similar paths! (the detail, I'll try & work out myself!)

thanks once again.