> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sqlbuild.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Model-Private Values

> Keep enums and constants inside one model when no other resource should use them.

Put an enum or constant directly in `MODEL()` when it belongs to one model and should not enter the
project-wide namespace.

```sql theme={null}
MODEL (
  enums (
    _state [OPEN, CLOSED],
  ),
  constants (
    _min_runners 7,
    _supported_countries ["GB", "FR", "HK"],
  ),
);

SELECT *
FROM runners
WHERE state = @enum("_state").OPEN
  AND runner_count > @const("_min_runners")
  AND country_code IN @const("_supported_countries")
```

## Where private values work

A model-private value is available in:

* The owning model's query
* Inline SQL hooks written in that model

It is not available in:

* Another model
* A child or sibling model directory
* A unit test or scenario
* A named SQL hook stored under `hooks/sql/`

Private names begin with exactly one `_`. Names beginning with `__` are reserved for SQLBuild.
Because the model owns the name, different models may each define `_state` without creating a
collision.

## Explicit types and rendering

Use `constant(...)` when a private constant needs an exact type or rendering choice:

```sql theme={null}
MODEL (
  constants (
    _usd_rate constant(
      type decimal,
      value "2.4700",
    ),
    _supported_countries constant(
      value ["GB", "FR", "HK"],
      render_as array,
    ),
  ),
);
```

## When a value becomes shared

Move the declaration out of `MODEL()` when another resource needs it. Remove the `_` prefix and put
it in the narrowest suitable enum or constant directory. See
[Declarations and Scopes](/concepts/declaration-scopes) for those advanced placement options.