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

# Substrate model

> Why 'substrate' rather than 'channel' — and the 23 substrates first-class in the EnfinitOS type system.

A **substrate** is the physical or virtual surface a piece of content
is rendered on. EnfinitOS treats substrates as first-class type
citizens — adding a new one is configuration, not a rewrite.

## The 23 substrates (plus the `ANY` wildcard)

`ANY` in the table below is a wildcard target, not a 24th substrate.

| Category                | Substrates                                                                                  |
| ----------------------- | ------------------------------------------------------------------------------------------- |
| **Out-of-home**         | `DOOH`                                                                                      |
| **Visual**              | `CTV`, `MOBILE`, `SOCIAL_FEED`, `GAMING`                                                    |
| **Spatial / wearable**  | `GLASSES`, `AR_CONTACTS`, `HUD`, `VOLUMETRIC`, `HOLOGRAM`, `WEARABLES`, `AMBIENT`, `NEURAL` |
| **Streaming & audio**   | `STREAMING`, `AUDIO`                                                                        |
| **Messaging**           | `MESSAGING`                                                                                 |
| **Environment**         | `AUTOMOTIVE`, `SMART_HOME`                                                                  |
| **Movement**            | `ROBOTICS`, `DRONE`                                                                         |
| **Broadcast / transit** | `SATELLITE`, `AVIATION`, `MARITIME`                                                         |
| **Special**             | `ANY`                                                                                       |

## Substrate-specific constraints

Each substrate brings constraints the platform must respect. The
constraint types are themselves first-class in the type system:

* **Spatial constraints** — geofences, polygons, altitude bands.
* **Temporal constraints** — windows, blackout periods, quiet hours.
* **Audience constraints** — age, consent, opt-out registries.
* **Content constraints** — substrate-appropriate format and policy.
* **Territory constraints** — broadcast / streaming territories.
* **Behavioural constraints** — automotive speed gates, drone
  altitude / no-fly zones, robotics kinematic envelopes.
* **Broadcast footprint claims** — satellite beam coverage.
* **Audio attention constraints** — voice-assistant prominence.
* **Opt-out registry constraints** — TCPA, PECR, DNC, CASL.
* **Consent records** — first-class auditable consent objects.

## Why this matters for the SDK

Render SDKs **compose** the substrate-agnostic Renderer Core. They
don't inherit from it; they compose it. The Drone SDK composes the
Robotics SDK, not the other way around. Adding a new substrate means
adding a new SDK with its substrate constraints and adapter shims —
the underlying rights / proof / metering plane doesn't change.

## Substrate readiness

Per-substrate shipping readiness is tracked openly in the
[substrate readiness matrix](https://enfinitos.com/developers#trust)
on the public developer hub.