1ef7220f__Guide___Salesforce_Developers__Details
[Field] Visibility [Details] 
Type picklist Properties Filter, Group, Nillable, Restricted picklist, Sort Description Specifies whether this feed item is available to all users or internal users only. This field is available in API version 26.0 and later, if Salesforce Communities is enabled for your organization. Visibility can have the following values: AllUsers—The feed item is available to all users who have permission to see the feed item. InternalUsers—The feed item is available to internal users only. Note the following exceptions for Visibility: For record posts, Visibility is set to InternalUsers for all internal users by default. External users can set Visibility only to AllUsers. On user and group posts, only internal users can set Visibility to InternalUsers.
UserFeed | SOAP API Developer's Guide | Salesforce Developers
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