As an example, you may design an empty inovice in a spreadsheet. You design
it, get all the formulae working, get it to autonumber on opening, or every
time you print an invoice, and to clean out the info - transfer to a detail
listing of invoices, or save the invoice as another name, etc. You want to
use this to do your inovicing,
If you save this as an XLA, you will always use this sheet to do invoicing,
but you will never save it as an invoice, and botch up all the work you have
done