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+SQL Language Extension: SET ROLE
+
+   Implements capability to change role in already establishment attachment.
+
+
+Author:
+   Alex Peshkoff <peshkoff@mail.ru>
+
+
+Syntax is:
+
+   SET ROLE rolename;
+   SET TRUSTED ROLE;
+
+Description:
+
+Makes it possible to set current role to one, granted to current user, or to one assigned
+to database attachment as trusted.
+By default trusted role is not assigned to the attachment. This behavior can be changed using
+appropriate authentication plugin and CREATE/ALTER MAPPING command. Well know sample of
+trusted role is RDB$ADMIN assigned to windows admins when windows trusted authentication is
+used.
+
+Samples:
+
+   SET ROLE manager;
+   select current_role from rdb$database;
+
+  Displays:
+
+ROLE
+=============================== 
+MANAGER