For my effort regarding the 'Adopt A Box' research project, I did find a couple of nuggets in the Reagan Library Reference.
Chapter 485, Section 8j:
That during the ceremony of hoisting or lowering the flag or when the flag is passing in a parade or in a review, all persons present should face the flag, stand at attention, and salute. Those present in uniform should render the right-hand salute. When not in uniform, men should remove the headdress with the right hand holding it at the left shoulder, the hand being over the heart. Men without hat merely stand at attention. Women should salute by placing the right hand over the heart. The salute to the flag in the moving column should be rendered at the moment the flag passes.Thus, men without hats should stand at attention when the flag is presented. The hand-over-heart tradition is for those wearing headgear.
Congressional Record – House, April 27, page 3720
Mark Clark (of Anzio fame) was promoted to Major General
James Doolittle (of Tokyo raid fame) was promoted to Brigadier General