This kinda looks like the Aussie style ruck. The Aussie version has an outside front pocket and top pocket, but the side pockets are do not have an open bottom. Here is a link...

http://www.unclesams.com/MilitaryClothin...39/Default.aspx

I used one in the field and kept a FAK in the outside front compartment and a poncho/poncho liner in the top compartment. I could fit a GI collapsible canteen in each side pocket (But it was very tight).
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Spemque metumque inter dubiis - Hover between hope and fear. (Vergil)