This attributes determines whether a multi-line text form field (an input where type = "text" and lines > 1) can be scrolled. By default this is "true", which means that although a box may only appear as to or three lines on the page, there is no limit to the number of lines it can contain. Setting this to "false" will limit the box to the number of lines that is displayed on screen.
This creates a text box that is limited to three lines of input
<input type="text" name="address" lines="3" scrollable="false"/>