We use a spreadsheet to log incoming inspections of products. I want to
monitor how long it takes between receipt and inspection; receipt is logged
into a different spreadsheet with date and time. I want to have the
inspection worksheet automatically date stamp when an inspection is
completed; I want to do this using IF(ISBLANK(xx),"",NOW()). The problem is
that everytime the spreadsheet is opened the time is recalculated. I can
turn off recalc, but at times it is necessary to do a recalculation. How can
I do a datestamp that will not change?

Thank you.