A row list is a comma separated list of values which tells the browser how to divide the document area into rows. The width of these rows, of course, is just the width of the document area, but the height and number of rows is determined by the actual values in the list. The number of rows is, simply enough, just the number of values in the list. There are four rows.
All rows have the same width, the width of the document area.
The top row, row 1, is 30 pixels high. The remaining document area is divided between rows 3 and 4, the bottom two rows. 3 and 4 share the remaining space because they are asterisk rows, but row 4 must be twice the height of row 3. Unfortunately, it is possible to specify a row list such that the total height of all rows is not equal to the document area's height. This kind of row list is called an improper row list , and though it is not necessarily bad, it can give unexpected results.