A location is a 4-floating vector. You can access to its components by pattern matching on them:

  let Location x y z w = Location 1 2 3 4

That type is strict and unboxed.

A texture coordinate is a 3D-floating vector. You can access to its components by pattern matching on them:

  let TexCoord r s t = TexCoord 0.1 0.2 0.3

That type is strcit and unboxed.

A normal is a 3-floating vector. You can access to its components by pattern matching on them:

  let Normal nx ny nz = Normal 0.1 0.2 0.3

That type is strict and unboxed.

A point is a single index that references the locations. It’s a canonical type that truly represents a polygonal point.

A line index is a pair of indices. LineIndex vi vti. vi references the locations and vti indexes the texture coordinates. If vti == Nothing, then that LineIndex doesn’t have texture coordinates associated with.

A face gathers several FaceIndex to build up faces. It has a least three vertices

A face index is a triplet of indices. FaceIndex vi vti vni is a face that indexes the locations with vi, the texture coordinates with vti and the normals with vni. An index set to Nothing means no information. That is, if vni == Nothing, then that FaceIndex doesn’t have a normal associated with.

An element holds a value along with the user-defined object’s name (if any), the associated groups, the used material and the smoothing group the element belongs to (if any). Those values can be used to sort the data per object or per group and to lookup materials.