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

# Key naming for Notifly integrations

> Use supported keys when sending custom user properties and event parameters from the Notifly SDK.

Custom user property keys in `setUserProperties` and event parameter keys in `trackEvent` must match `^[A-Za-z][A-Za-z0-9_]*$`.

* Start with an uppercase or lowercase English letter (`A–Z` or `a–z`).
* After the first character, use only English letters, digits (`0–9`), or underscores (`_`).
* Spaces, Korean characters and other non-English letters, and special characters such as `.`, `$`, and `^` are prohibited.

For custom keys, use names such as `delivery_address` and `productId2`. Use built-in user property keys such as `$email` and `$phone_number` as defined by Notifly.

Notifly still stores data sent with keys that fall outside this format, but some features may be unavailable. A user property containing a period is unavailable in campaign condition search, user lists and details, and CSV exports of all users. It is also hidden in **Property management**, which prevents you from configuring encryption for it. [User property and event parameter keys](https://docs.notifly.tech/en/user-guide/users/key-naming.md#keys-containing-periods)


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