Hi, this is with a July-3rd snapshot, and what strikes me as quite strange behavior: <hansl> nulldata 20 series check = 0 check[1] = NA check[10] = 1 loop tau = 1..$nobs     eval check[tau]    # first with NA as expected     if check[tau] == 1         print tau    # expect only 10, get 1 and 10     endif endloop </hansl> Trying "if NA == 1" on the console (or also "if check[1] == 1") gives an "indeterminate" error message, which seems correct. Only inside the loop does it act weirdly. thanks sven