Need help knowing what a set of numbers mean on his war grave. Here's a picture of his grave post war. I'm confused by the numbers 549.533. Might this be an identification number for a unit? It shows his birth date in 7.10.00 and his death in 25.10.45, after the war. Does this mean he was a pow? Anyways here's the photos. (Btw I'll have all of my other info I learned transferred to here by a mod and have useless stuff not included).
Here's the back