Side bar..
Actually, correct me if I'm wrong but I think that first statment WAS correct. A while back, someone on FR informed me the flag should only be flown half mast by presidential order (national day of mourning, etc).
Is that correct?
Only if you're over water. Flags over land fly at half-staff.
According to flag etiquette, the national standard flies at half-staff upon the death of a past or present President of Vice-President or upon Presidential proclamation.