vtk-m2/docs/changelog/vec-typedefs.md

Add aliases for common Vec types

Specifying Vec types can be verbose. For example, to simply express a vector in 3-space, you would need a declaration like this:

vtkm::Vec<vtkm::FloatDefault, 3>

This is very verbose and frankly confusing to users. To make things easier, we have introduced several aliases for common Vec types. For example, the above type can now be referenced simply with vtkm::Vec3f, which is a 3-vec of floating point values of the default width. If you want to specify the width, then you can use either vtkm::Vec3f_32 or vtkm::Vec3f_64.

There are likewise types introduced for integers and unsigned integers (e.g. vtkm::Vec3i and vtkm::Vec3ui). You can specify the width of these all the way down to 8 bit (e.g. vtkm::Vec3ui_8, vtkm::Vec3ui_16, vtkm::Vec3ui_32, and vtkm::Vec3ui_64).

For completeness, vtkm::Id4 was added as well as vtkm::IdComponent2, vtkm::IdComponent3, and vtkm::IdComponent4.