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.
preÂ·curÂ·sor. That which precedes another or from which another is derived, applied especially to a physiologically inactive substance that is converted to an active enzyme, vitamin, hormone, etc., or to a chemical substance that is built into a larger structure in the course of synthesizing the latter.he storm increase, the flashes succeeded one another more rapidly, the thunder began to growl, and the wind, the precursor of a hurricane, whistled in the plumes and the hair of the horsemen.