Every tile from a single suit.
A coherent older lineage scores this 6. We score 7, the tournament reading. The full comparison
Every tile in the hand is from one suit, with no honours at all. It is seven faan, one of the largest ordinary patterns before the limit hands.
The sets may be chows, pungs or kongs, in any mix. The single restriction is the suit, which is what makes it hard.
Only commit with a strong start, meaning six or more tiles of one suit in your opening hand. Every honour you hold is a wasted tile here, which is what separates this from Mixed One Suit. The hand is very visible once you have discarded two suits, so expect the table to stop feeding you.
Chasing it from a Mixed One Suit hand by throwing away good honours. You give up three guaranteed faan, plus any dragon or wind pungs, for a hand that is much harder to finish. Take the upgrade only if the honours were doing nothing anyway.
With Common Hand it is seven plus one for eight. With All Pungs it is seven plus three for ten. It cannot combine with Mixed One Suit, since one demands honours and the other forbids them, and the calculator scores the higher of the two.
Can I hold one dragon in Pure One Suit?
No. Any honour makes it Mixed One Suit at three faan instead of seven.
Do the sets have to be pungs?
No. Chows, pungs and kongs are all fine. Only the suit matters.
Which suit is best?
The one you already hold most of. No suit scores more than another.
Play Mahjong Winds
Every win shows its faan line by line, using the table on this page.