Hi Mark,
Thanks for the very detailed explanation! I was thinking a good workflow for my project would be create a spreadsheet dynamically using PHPExcel
then open (point ZOHO via a post to the document url ) it in ZOHO spreadsheets and then save it back to my site. See this for the gist of what I am doing:
https://apihelp.wiki.zoho.com/Open-Document.html
Thanks again,
Jim