BOF:0-1024 (can be unlimited preamble, but we want to anchor near the beginning of the file for most cases).
Must have vertices:
v <space> 3 x space separated floating point values that can have a negative value or not representing x, y, z. w is optional, line ending.
Later, the vertices must have a face:
f <space> 3+ integer values, can be negative, separated by space. Faces count from 1. PRONOM uses this minimally viable set, however each face can have values for ‘vertex textures’ and ‘vertex normals’ - if present, these values are separated by /. Each row ends in new line character