Final answer:
If the number of authorized oak leaf clusters exceeds four and will not fit on a single ribbon, additional clusters can be displayed on a second ribbon worn beneath the first one.
Step-by-step explanation:
If the number of authorized oak leaf clusters exceeds four and will not fit on a single ribbon, the additional clusters are usually displayed on a second ribbon worn directly beneath the first ribbon. The second ribbon can be placed either above or below it, depending on the regulations of the specific military or organization. The purpose of displaying the authorized oak leaf clusters on a second ribbon is to maintain the integrity and appearance of the original ribbon while recognizing additional awards or achievements.