On Fri, 7 Jun 2013, Artur Tarassow wrote: The old behavior was due to an undocumented hack whereby a date string such as "1978:3" could be used "as is" in arithmetic. This was just too sloppy and it has been discontinued. If you want to use a date in arithmetic you have to convert it to a proper scalar via the obsnum() function. In principle, your command smpl @first @last-Tdiff should work if rephrased as smpl @first obsnum(last)-Tdiff but this didn't work because the internal string variable to hold the sample limit was too small so that "obsnum(last)-Tdiff" was getting truncated. That's now fixed in CVS. However, it's much more elegant to use the increment or decrement form of the smpl command for this sort of thing. Allin Cottrell