# Objective
`MeshVertexAttributeId` is currently a wrapper type around a `usize`.
Application developers are exposed to the `usize` whenever they need to
define a new custom vertex attribute, which requires them to generate a
random `usize` ID to avoid clashes with any other custom vertex
attributes in the same application. As the range of a `usize` is
platform dependent, developers on 64-bit machines may inadvertently
generate random values which will fail to compile for a 32-bit target.
The use of a `usize` here encourages non-portable behaviour and should
be replaced with a fixed width type.
## Solution
In this PR I have changed the ID type from `usize` to `u64`, but equally
a `u32` could be used at the risk of breaking some extant non-portable
programs and increasing the chance of an ID collision.
defeeb375b