template parameter for sampled texture types is always a 32-bit scalar numeric type

[dneto0]

Currently the diagram says the template parameter, the "sampled type" is "numeric scalar"
But it's more pinned down than that. It's one of the three 32-bit numeric types.

It denotes the component type of the result after conversion to the in-shader representation. Vulkan/SPIR-V only supports the full-fat numeric types, and so WGSL inherits that.