> For the complete documentation index, see [llms.txt](https://docs.verifone.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.verifone.com/adk-os-platform/readme/lifecycle-modes-and-startup.md).
# Lifecycle, modes, and startup
Understand device lifecycle states, APP-DEV mode, warrantied keys, and the VOS3 startup flow.
Use this page to understand how a VOS3 device moves through its lifecycle, which operating modes are available, and how the platform boots.
## Lifecycle overview
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## Production and application development modes
VOS3 devices support two main operating modes:
* **Production mode**
* **Application development mode**
Production mode is intended for live device operation.
In this mode, the full security model remains enabled.
### APP-DEV mode
Application development mode supports development and testing.
In APP-DEV mode:
* a blinking banner shows that the device is in APP-DEV mode
* applications can use default development signing instead of production signing
* console access is enabled
* debugging tools are enabled
* test warrantied keys are loaded so test payment keys can also be loaded
{% hint style="info" %}
Conversion to APP-DEV mode is provided by Verifone.
Converted devices can be ordered separately.
{% endhint %}
## System warrantied keys
The system ships with a set of warrantied keys.
| **Warrantied Key** | **Details** | **Key Type** |
| ---------------------------------------- | ----------------------------------------------------------------------------------------------------------- | -------------------------- |
| VRK Key: Verifone Remote Key Loading Key | Used to encrypt and decrypt the VRK payload for RSA, or to establish the VRK payload transport key for ECC. | ECC-521 |
| Authentication Key (Authex or AuthN) | Authenticates the device to external services such as VHQ or a customer TMS. | RSA-2048
ECC-521
|
| Pairing Key | Authenticates a connected Verifone device and establishes trust for key exchange between Verifone devices. | RSA-2048
ECC-521
|
| System Signer | Reserved for Verifone private use. | ECC-521 |
## System startup process
The following diagram shows the startup flow and the main participating components.
System startup passes through multiple layers.
These layers include boot loaders, system verification, and launcher startup before system services and the Multi-Application Controller start.
User applications are started by the system launcher.
The launcher checks authenticity and permissions based on the MAC manifest and the application manifest.
If no signing sponsor is found, the system automatically enables the system downloader.
After startup completes, the MAC desktop provides access to the installed control panels.
---
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