> For the complete documentation index, see [llms.txt](https://yudu-sentinel.gitbook.io/sentinel-documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://yudu-sentinel.gitbook.io/sentinel-documentation/basics/faqs.md).
# FAQ's
Common questions and answers
#### General
What is the difference between 'Files' and 'DRM Documents'?
Files are regular uploads you manage and reuse; DRM documents are published, protected PDFs.
What is a 'Global' contact?
A global contact is a System Contact which automatically appears visible in all current and future created spaces.
This is a convenience feature - which means instead of manually assigning a common contact manually to each space they can be assigned automatically.
What is a 'Global' DRM document?
A global document is a DRM document which is automatically available in all spaces for assignment to end users.
#### Mass Notification
Why is my broadcast message status 'Failed'?
A message can fail for various different reasons:
* Email addresses which no longer exist.
* Invalid phone numbers.
* Attempting to send to phone numbers in unsupported geographical regions.
* Rejections for messages which potentially contain spam.
* Bad Signal.
Please contact YUDU Sentinel support for more advice if you are unsure why any particular mass-notification messages has failed.
#### Spaces
What are Spaces?
Sentinel Spaces are used to securely divide resources into logical groups for planning, incident handling, public relations or any other separation required of Business continuity.
Tailored spaces match each potential threat and deliver faster response times, quicker resolution and reduced harm to people and organisations.
Spaces are created and configured in advance and ready for immediate activation.
What is a Space controller?
Space Controller is a special role that is assigned to an assigned space User.
A space controller can perform more actions in a Space compared to a normal user.
* Attach Space Files and pin the files to the Space Dashboard for all Space Users to access
* They are designated the 'go to' person for the Space and are listed on the Space Dashboard
* Manage Space settings from within the space (without being a system administrator)
#### Passkey Authentication
Why is my passkey not showing up when I try to sign in?
Passkeys are tied to the device and authenticator (e.g. iCloud Keychain, Google Password Manager) where they were created. If you're on a different device or browser, your passkey may not be available unless it syncs across devices via your account (e.g. Apple ID or Google account).
I set up a passkey before, but it doesn't work?
This can happen if you:
* Cleared your browser data or reset your device
* Removed the passkey from your password manager or OS settings
* Unlinked the account that was syncing your passkeys (e.g. signed out of iCloud)
* The passkey was deleted from our system.
Why can't I use passkeys on my browser?
Passkeys require WebAuthn support. Most modern browsers support this (Chrome 108+, Safari 16+, Firefox 119+, Edge 108+). If you're on an older browser, an unsupported browser, or a private/incognito window with restricted permissions, passkey login may not work.
Can I use a passkey if I've lost access to the device I created it on?
If your passkey was synced (e.g. via iCloud Keychain or Google Password Manager), you can access it after signing back into that account on a new device. If it was device-bound and the device is gone, you'll need to sign in via password authentication and create a new passkey.