In my Daily Sales database, I had to layouts. In one I had all fields set so that entry in Browse Mode was prevented if the date was more than 3 days into last month. We allowed three days to balance the month for closing. After that it was blocked.
Interesting. By what mechanism did you get FMP to do this?
The script to look up a date or range of dates checked with a IF/THEN
The Found Set was the same, either way. If the Date, or first date of the range was in that protected range, it went to the layout that did not allow editing. Navigation could only happen through doing a Find.
1) it's the easiest, but not the most user friendly approach as it allows the user to attempt an change of the data and then throws an error message where they have to revert the data.
Better would be to use a version of your example as a "lock expression" in Manage | Security for your users' privilege set(s). This would keep all but [full access] users from being able to change the data.
See "Editing record access privileges" in FileMaker Help and check out this particular sub section: "Entering a formula for limiting access on a record-by-record basis" for a description of how to set this up.
Oh boy, that looks like it'd do the trick but I don't think I'm ready to take the time to implement user control on our database yet.
For my future reference: http://www.filemaker.com/help/13/fmp/en/html/passwords.14.20.html#1028570