All pulse sequences usually start with the ze command and finish with the exit command

The command ze serves the following purpose:

1. To reset the scan counter (displayed during acquisition) to 0
2. To enable the execution of dummy scans. This will cause the pulse program command go= label to perform DS dummy scans before accumulating NS data acquisition scans. If you replace ze with zd, go= label will omit the dummy scans
3. To reset phases to the beginning of phase programs (phase lists)

The exit command signals the end of the pulse program.

The standard way to implement such commands in a pulse program (see zg) is:

ze ... ... ... exit