Text cursor

In most command line interfaces or text editors, the cursor is an underscore, a solid rectangle, or a vertical line, which may be flashing or steady, indicating where text will be placed when entered (the insertion point). In the old days of text mode displays, it was not possible to show a vertical bar between characters to show where the new text would be inserted, so an underscore or block cursor was used instead. In situations where a block was used the block was usually created by inverting the pixels of the character using the boolean math exclusive or function. On text editors and word processors of modern design on bitmapped displays, the vertical bar is typically used instead. Some older graphical user interfaces such as OPEN LOOK used a caret-shaped insertion marker.[citation needed] Still today, the text cursor is sometimes called caret. Some details of the vertical bar's origins have been described in Bill Moggridge's Designing Interactions (ISBN 0262134748).