From ECWolf Wiki

The textures lump is used to define composited textures. The lump is supported by code from ZDoom and should be mostly identical to ZDoom's TEXTURES lump (note that ECWolf does not support deprecated features).

ECWolf does add the ability to assign textures to art indexes for art screens. It is not recommended that you use this feature since graphics can be given by name. The syntax is "artindex number, texture".