When the commander is in, his or her guidon is displayed for everyone to see. When the commander leaves for the day, the guidon is taken down. It is an honor to be the guidon carrier for a unit, known as a guidon bearer or guide. He or she stands in front of the unit alongside of the commander (or the commander's representative), and is the rallying point for troops to fall into formation when the order is given.
Preclude is defined as  to prevent something from happening or to prevent someone from doing something. An example of preclude is when you take someone's keys away so that they cannot drive.
presume verb (BELIEVE) C1 [ T ] to believe something to be true because it is very likely, although you are not certain: [ + (that) ] I presume (that) they're not coming, since they haven't replied to the invitation.