Cursors should have distinctive visual features (shape, blink, or other means of highlighting).
Additional Information:
A cursor is the most immediate and continuously available form of user guidance, since it will generally mark the current focus of user attention. Different cursor formats may denote different operational conditions. If that is done, each of those different cursors should be distinctive from other displayed items, and from each other. An underscore cursor would be difficult to see on a display of underscored text, or on a graphical display containing many other lines. If multiple cursors are used on the same display (e.g., one for alphanumeric entry and one for line drawing), then each cursor should be distinguishable from the others.