Field name: email

Possible values: Any email address

Field name: country

Possible values: ISO 3166 Alpha2-code

Field name: os

Possible values: Android, Chromium OS, iOS, Linux, Mac OS, Windows

Field name: browser

Possible values: Chrome, Safari, Mobile Safari, Edge, Firefox, Samsung Browser, Opera, Android Browser

Field name: language

Possible values: ISO 639-1 language code

Field name: push_subscribed

Possible values: ISO 8601 date

Field name: app_installed

Possible values: ISO 8601 date

Field name: domain_name

Possible values: a domain or subdomain (without https://)

Field name: install_path

Possible values: any relative URL path

Field name: push_path

Possible values: any relative URL path

You can also set your own fields by connecting your own user data, and then using this for segmenting recipient when sending push notifications.