We often hear players refer to the letter "c" displayed to the right of a hand on the NMJL card as a "closed" hand. The proper term is a "concealed" hand. Incidentally, some players refer to the "x" hands as "open" hand . The property term for this type of hand is "exposed". It is acceptable to use closed for concealed and open for exposed with no penalty incurred.
A wall game occurs when all tiles have been exhausted and no one has declared mah jongg. There are several theories as to why a wall game might occur. "Dogging" to early by beginner players and or "Dogging" at the appropriate time during a game can attribute to a wall game. Experienced players might experience more wall games by virtue of very defensive play.
