The library administrator can choose to show guided search fields on the Advanced Search Screen.
If the guided search fields are displayed, you can enter text on all three lines. If you do not enter terms on line one, the operator to the left of line two is ignored. (You can begin a search string on line two.)
After you click Search, the input from all three lines is joined together on the first line. And takes precedence over or when the system groups items together. Parentheses are assigned based on this logic. To force grouping, you can enter the parentheses or place "grouped" expressions together in a single input field.