TEXTMAP

TEXTMAP contains all the map data that a modder adds to an UDMF map in an level editor, and replaces the THINGS, VERTEXES, LINEDEFS, SIDEDEFS and SECTORS lumps from the binary map formats.

While the format is plain text, it is not advised to attempt editing it through a text editor rather than a specialized map editor. The format is legible enough to be parsed or created by various tools and scripting language (including Perl or PHP), but is mostly illegible for a human.

See Universal Doom Map Format for more information.