Being the author can I add a few words of reassurance?

There aren't any malicious things built into any of the spreadsheets that I have put into the public domain. They are purely Excel spreadsheets.

It's the nature of the Internet that stuff gets "borrowed" and placed on other sites. When the first version of How Many Fills was released it was given away in exchange for a promise to donate £2 to breast cancer charity. Lots of members on here did just that. Within a short while the spreadsheet had been hijacked and re-promoted on various US based sites as a free download or to sponsor the site owner. I pointed out that they were basically robbing a cancer charity of donations but it cut no ice. I can't vouch for the integrity of spreadsheets you might download elsewhere, all I can say is when they leave me they are clean.

One or two of my later projects include macros in the spreadsheet, and Excel will often warn you that you are about to open a file containing macros, giving you the option to enable or disable at that time. That's your choice, but the macros are there for the functionality of the sheet, nothing else. If you choose to disable you may find the sheet does not do all that it should.