The new SQL-2008 compliant USAGE permission was introduced in Firebird 3.0 to protect metadata objects other than tables, views, procedures and functions. This feature is supported by IBExpert from version 2014.01.01 onwards.
Syntax pattern
GRANT USAGE ON <object type> <name> TO <grantee list>
[<grant option> <granted by clause>]
--
REVOKE USAGE ON <object type> <name> FROM <grantee list>
[<granted by clause>]
--
<object type> ::= {DOMAIN | EXCEPTION | GENERATOR | SEQUENCE | CHARACTER SET | COLLATION}
Notes: The initial USAGE permission is granted to the object owner (user who created the object).
In Firebird 3.0 Alpha 1, only USAGE permissions for exceptions (CORE-2884) and generators/sequences (gen_id, next value for: CORE-2553) are enforced. Permissions for other object types will be validated in subsequent releases.
Source: Firebird 3.0 Release Notes by Helen Borrie (Collator/Editor): 23 July 2013 - Document v.0300-06 - for Firebird 3.0 Alpha 1