LDAP syntax filters

=	Equality
>=	Greater than or equal to (lexicographical)
<=	Less than or equal to (lexicographical)
&	AND, all conditions must be met
|	OR, any of the conditions must be met
!	NOT, the clause must evaluate to False

all user object filter:  (&(objectCategory=person)(objectClass=user)) 

a more efficient all user object filter: (sAMAccountType=805306368)

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