[0-9a-fA-F])*
- _Whitespace_: (\s)*

As an example, this is how `Flags::A | Flags::B | 0x0c` can be represented as text:

```text
A | B | 0x0c
```

Alternatively, it could be represented without whitespace:

```text
A|B|0x0C
```

Note that identifiers are *case-sensitive*, so the following is *not equivalent*:

```text
a|b|0x0C
```