A printer MUST support the values top, middle, and bottom for the valign attribute of the td, th, and tr elements
Tests for assertions 51, 52, 53, 54, 58 
Table 3: Values of valign for tr
| Row 1 | Top Middle
 Bottom
 | valign=top | 
| Row 2 | Top Middle
 Bottom
 | valign=middle | 
| Row 3 | Top Middle
 Bottom
 | valign=bottom |