Dora
Dora (ドラ) is a feature to the game, where possession of specific tiles instantly grants the hand 1 han per tile. Regardless, hands must still possess a yaku in order to score, regardless of the number of dora in the hand.
The dead wall
Every mahjong hand session has 14 tiles set aside from the regular tile draw and discard processes. These tiles are designated as the dead wall, and they are considered to be out of play. Among the dead wall, one tile is flipped and revealed for everyone. This tile is assigned as the dorahyouji (ドラ表示), or "dora indicator". Tiles marked as dora are indicated as the next tile in the sequence. For example, if the dora indicator shows , then the dora tile is .
Dora order
This lists the complete dora order. As a repeat, the dora is the next tile within each of the following orders. Dora are not "cross indicated" among the different suits. Furthermore, the dora order loops.
Wind order
Dragon order
Red 5
If included in the game, these "red fives" may also count as dora, regardless of the dora indicator. If the dora indicator is a four, the red five of the same suit counts as two dora.
Ura dora
This applies only to hands won using riichi. In the event a riichi declared hand has won, the tiles underneath the dora indicator(s) are revealed. These newly revealed tiles serve as additional dora indicators. Potentially, such hands may potentially gain substantial value, just off of the ura dora.
If there are multiple identical indicators, each indicated tile counts as multiple dora correspondingly.
Kan dora
After a call for kan, additional dora indicators are flipped. These are tiles next to the dora indicator counter clockwise on the dead wall. Depending on the rules and/or formality of the game, the timing for flipping the kan dora during a kan procedure may vary. Casual games will simply flip the kan dora immediately after kan. More technical games will differentiate between the kan types, where the kan dora may be flipped after the player makes a discard.
Likewise, in the event of riichi, the ura dora underneath the kan dora are also revealed, as kan ura dora.