Vertex

Linedefs are connected to vertices, which are nothing more than coordinates in the map.

The vertices for a map are stored in the VERTEXES lump, which consists of a raw sequence of x, y coordinates as pairs of 16-bit signed integers. The bytes are in little-endian order (least significant byte first).

Due to the 16-bit signed format, each coordinate can range from -32768 to +32767.