Normally, there are four to ten per level. One of them is chosen at random each time a player joins or respawns. A respawning player will telefrag any player or monster who happens to be standing on that deathmatch start. In the WAD file, deathmatch starts are stored as Things. However, since they have no associated sprites, they are not visible. The maximum number of usable deathmatch starts in vanilla Doom is ten. If a map contains more than ten deathmatch starts, only those with the ten lowest Thing numbers are used.