Unable to name constraints other than foreign keys

I'm attempting to give a name to some constraints.
For primary key I tried this (I'm using dbdiagram.io):

```dbml
Table "department" {
"department_id" int [not null, increment]

Indexes {
department_id [name: "pk_department", pk]
}
}
```

Although, it looks like that is not possible:
`Expected "name:", "note:", "type:", "unique", comment, or whitespace but "p" found.`

Am I doing something wrong? Is this not supported?

I also would like to know if it is possible to name other constraints like default and unique (not the unique index, but the constraint)

Thank you.