How to display a changeover even when there are no previous operations

Steps:

1,In each setup table, specify “!” for the property “Item L”, “Resource L”, or “Previous spec”.
2,When no left operations exist, the setup time of the record for which “!” is specified will be used.
3,You can make the above setting only for “Item L”, “Resource L”, or “Previous spec”.
4,No left operation means that there is actually no use instruction for that resource in the infinite past.