Use the Group window to add or modify a group of conditions. Once you have a group, you can add conditions or sub-groups to it. A group can be one of two types:
And - A row in the table must satisfy all the conditions in this group in order to show up in the query results.
Or - A row in the table can satisfy one or more of the conditions in this group in order to show up in the query results.
If you are adding a sub-group to an existing group, the new group will automatically default to the opposite type. This is done to make your job easier, since there is no logical reason to have a sub-group that is the same type as its parent. Regardless, the software will allow you to override the default and arrange your groups any way you see fit.