On page 209 in "A Time of War", it is said that the shield is to be treated as Barrier Armor, and it provides full cover when crouched.
Does the shield do anything for a character when said character is not crouched, and how would this work with the optional hit location rules?
The way I would Interpet that is:
First you determine the size of the shield,once you have that, you determine how much of the characters using the shield for cover would be blocked or obscured by the shield. That then determines how much cover it provides, and what if any locations would be covered or blocked from being hit by attacks past the shield.
To consider historical shields the Roman "Tower" shields might cover said Roman from knee to chin for instance in that case the characters would likely have 3/4 cover and more if they crouched or ducked a bit.
A kite shield might provide 1/4 or 1/2 cover depending.
Hope it helps
Edit stupid auto correct on my tablet .