## Schedule predicate and port types

The schedule predicate selects the port type kind of every input and
output of the op. The two cases are mutually exclusive.

| Schedule    | Port type                  | Uniformity                              |
|-------------|----------------------------|-----------------------------------------|
| `spatial`   | `!fabric.bits<W>`          | All ports must share the same `W` (>= 0). |
| `temporal`  | `!fabric.bits_tag<W, T>`   | All ports must share the same `(W, T)` (`W` >= 0, `T` >= 1). |

Spatial ports may not use `bits_tag`; temporal ports may not use `bits`.