Parentheses around a group of lines in a selection statement tell the computer to implement those lines first when evaluating the statement -- that is, to give them the highest precedence. By grouping lines together and defining the order of operation, parentheses can provide a large degree of flexibility when building a selection statement. Typically, it is easier to add parentheses and define the order of operation in the selection statement after all lines have been added. To add parentheses to your selection statement, follow these steps.
With your mouse, highlight the selection lines which will be between the parentheses.
Take note of whether there is a "Not" in the lines you are grouping. If the "Not" is on the first grouped line, it will be placed outside the parentheses, and will apply to the entire grouped sub-statement. A "Not" on any other line will be placed inside the parentheses and will still apply only to the line it is on.
Click Add (...). Parentheses will surround the lines you had highlighted.
To remove parentheses from your selection statement, follow these steps.
Highlight the selection lines that are enclosed by the parentheses you want to remove.
The lines you highlight must contain one or more balanced sets of parentheses.
Click Delete (...) to delete the parentheses that surround the highlighted lines, or Del All (...) to delete all pairs of parentheses within those lines.