# interaction toy.hold

Describes the entry `toy.hold` at version `0.1.0`, registered by `mime.testing.toys._entries.ToyHold`.

## At a glance

- interaction `toy.hold`, version `0.1.0`, namespace `toy`
- Nodes: [`ToyHoldNode`](../../nodes/ToyHoldNode.md)
- Undocumented, so with no equations to link: [`ToyHoldNode`](../../nodes/ToyHoldNode.md)
- Derivative: `exact`
- Validity: none declared

## What it models, and when not to use it

No hand-written part: this entry's source has not been written (the docs walk counts it).

## Settings

| Setting | Type | Default | Dimension | Role | Default's kind |
|---|---|---|---|---|---|
| `gain` | `Annotated[Quantity, Velocity]` | `{"unit": "m/s", "value": 0.5}` | velocity (m/s) | none declared | none: required |

Each role and default's kind is the entry's `setting_roles` (`mime.registry.SettingRole`); a setting that declares none is required.

## Roles, reads and deliveries

Roles, bound by keyword when the entry is attached: `body` (body), `field` (field).

Reads:

| Label | Reads |
|---|---|
| `push` | field [`toy.field.push`](../../vocabulary.md#namespace-toy) at the points of body [`toy.body.position`](../../vocabulary.md#namespace-toy) |

Delivers:

| Label | Role | Into the target |
|---|---|---|
| `hold_z` | body | [`toy.body.hold_z`](../../mechanisms/equality_constraint.md) |

## Nodes it builds

- [`ToyHoldNode`](../../nodes/ToyHoldNode.md)

Declared in `builds`; the node walk compares it with what a round-trip case builds.

## Gradient status

The derivative through this entry is `exact`, the derivative of what it computes.

## Validity

none declared

## References

none declared

## Other declarations

| Class variable | Type | Value |
|---|---|---|
| `holds_off` | `ClassVar[str \| None]` | `null` |
| `id_roles` | `ClassVar[tuple[str, ...] \| None]` | `null` |
| `moving` | `ClassVar[bool]` | `false` |