What are Buddhist flags for?

The editors of Wisdom Quarterly explain

We don't have to go trekking in the Himalayan foothills to want colorful flags (etsy.com)

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The universal Buddhist flag (theflagshop.co.uk)

The Buddhist flag is a beautiful rainbow of inclusion. It is blue, yellow, red, white, orange (or saffron). It is about the unity of schools and sects, now grown out of all proportion in diversity. The ancient Theravada (Teaching of the Elder Enlightened Disciples of the Historical Buddha) school is one thing, but the much larger Mahayana (Great Vehicle) school is so scattered as to not deserve to be called a single school. It includes Hinduism, New Age, and catholic Tibetan Buddhism, and just about anything anyone wants to call Buddhism. But the Himalayan schools (Nepal, Bhutan, Northern India, Ladakh, Darjeeling, and Tibet) prefer the term Vajrayana, a subcategory of Mahayana. How could one flag fit all of this diversity? Most Americans would sooner recognize the Himalayan prayer flag made famous by Tibetans in exile. It seems all mountain people have a custom of flying little flags in the wind to spread well wishes to the mountain spirits and weary travelers.

With all the variety in Buddhism, there had to be diversity in flags (Wikipedia).