I am wondering how to say that the flag is flying at the middle of the post. I saw the following sentences, but I am not sure if they are right since one of them does not have the artical "the" in it.
"Obama ordered that flags be flown at half staff."
"The flag is flying at the half mast today. "
"Obama ordered that flags be flown at half staff."
"The flag is flying at the half mast today. "