A recalculation engine version stamp is employed to determine whether a spreadsheet program file should be fully recalculated upon opening. When a spreadsheet program file is recalculated and saved, a recalculation engine version stamp is written to the file. The recalculation engine version stamp corresponds...http://www.google.ca/patents/US6523167?utm_source=gb-gplus-sharePatent US6523167 - Spreadsheet recalculation engine version stamp
