Hi Bob
I want to do this as the spreadsheet will produce data for an aircraft loadsheet which is a legal document and as such must be approved by an aviation authority. If the source data is changed it could be possible to produce a document that appear correct but is in fact dangerous. Protection will protect the document to some extent but it is relatively easy for anyone can beat the password protection there.
To make the sheet look not like a spreadsheet but a stand alone program would make it more readily approvable for legal reasons.
cheers
nobby