References
You can reference other roll formulas by ID using `@{id}` or `@{id}[label]`. This is useful for modular or reusable roll components.
`@{damage}` - Use the roll formula stored under the reference "damage".
`@{bonus}[extra]` - Use the roll formula stored under "bonus" and label it "extra".
IDs may consist of letters, digits, underscores, and dashes (`[a-zA-Z0-9_\-]`) but must not contain spaces, dots, or other symbols.