NOREPL turns off the replacement mode option (REPL). REPL specifies that series are to be updated rather than completely replaced when the current sample under which they are being computed does not cover the complete series.
NOREPL ;
Usage
The REPLace mode is the default; use NOREPL if you do not want previously existing series updated when they are modified. For example, use the REPL mode to create a series element by element with a DO loop and SET statements. Later on, if you want to recreate the same series with a slightly different sample, the REPL mode could cause the old observations to be mixed in with the new, so you might want to use NOREPL just for safety.
REPL ;
SMPL 1 10 ; GENR D = 0 ;
SMPL 11 20 ; GENR D = 1 ;
NOREPL ;
This creates a series named D which is zero for observations 1 through 10, and one for observations 11 through 20.