Rules for Using + and -

You must follow the + or – with a space.

You can add or remove any number of elements with one statement. Separate each element with a semicolon.

You can specify + elements even if no assignments had previously been made. The result is that the elements are now assigned.

You can specify – elements even if no assignments had previously been made. The result is that the set’s complement is assigned. Using the previous example, specifying:

RunWhen: - regression

when no RunWhen assignment had previously been made results in the values UI and smoke being assigned.