anchor.diff:  
   === Access control and user permissions
   
  -Being logged in to Annalist does not, of itself, grant permission to access or modify any Annalist data - except in a very broad sense covered by `_default_user_perms` (see below).  That is controlled separately by _user permission_ records, which may be created for any collection ovcerv which the user is granted access permissions.
  +Being logged in to Annalist does not, of itself, grant permission to access or modify any Annalist data - except in a very broad sense covered by `\_default_user_perms` (see below).  That is controlled separately by _user permission_ records, which may be created for any collection ovcerv which the user is granted access permissions.
   
   When a user is logged in to Annalist (using OpenID or local credentials), their session is associated with a user identifier (user_id) and an email address, as well as some descriptive information.  The user_id alone is not a secure basis for access control, as Annalist allows anyone to create a new user_id through the OpenID based login process.  Rather, it is assumed that the associated email address has been properly checked as associated with the logged-in user:  this verification is something that should be handled by any OpenID identity provider (such as Google) worthy of being used as such.  Annalist uses the combination of user_id and email address as a reliable authenticated identifier, with which access permissions are associated.  Different user_ids may bve associated with the same email address, possibly corresponding to different roles of the authenticated user;  each such combination is associated with its own set of permissions. (Technically, Annalist internally uses a mailto: URI as an authenticated user identifier, and uses different forms of URI for some special cases.)
   
  
positive.code: 
  Now click on the 'New' button:
  
  image::screenshots/Front-page-collection-created.pngg[alt="Front page showing new collection created"]
  
  Click on the link in the Id column to view the new collection:
  
  
negative.code: 
  Annalist specifies two special users for the purpose of defining default access permissions.  As these are not "real" users, they do not have email addresses, so they are assigned Annalist-specified URIs rather than `mailto:` identifiers.
  
  * User_id `_default_user_perms`, URI `annal:User/_default_user_perms`: these permissions are used for any logged-in user for whom specific permissions are not applicable.
  
  * User_id `_unknown_user_perms`, URI `annal:User/_unknown_user_perms`: these permissions are used for any unauthenticated access, and as such define the level of public access available to a site or collection.
  
  Default permissions may be defined at site-level using the `annalist_manager` commands described above, or for a particular collection by creating user permissions for the indicated user_id and URI through the Annalist web interface.
  
  