From Japanese mahjong wiki
<KyuuW> How about double stacked tiles? <KyuuW> Y'know, for added kan <KyuuW> If I have to, I'll produce the images
<KyuuW> Well, there were those "tiles" to be used for "paifus" <KyuuW> I have to look at those again
- Add to the manual the info from here User_talk:Bps about paifu arrows.