Complex sentence: As soon as he arrived at the demarcation line he was told he was limited to 37-50-175, as per the "Berlin Agreement:" 37 officers, 50 vehicles, and 175 men.
Split into simpler sentences: As soon as he arrived at the demarcation line he was told he was limited to 37-50-175, as per the "Berlin Agreement". This stipulated, so they said, that he could pass with no more than 37 officers, 50 vehicles, and 175 men.