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*** a/doc/src/sgml/func.sgml
--- b/doc/src/sgml/func.sgml
***************
*** 82,89 ****
       <member><literal>NOT</></member>
      </simplelist>
  
!     <acronym>SQL</acronym> uses a three-valued Boolean logic where the null value represents
!     <quote>unknown</quote>.  Observe the following truth tables:
  
      <informaltable>
       <tgroup cols="4">
--- 82,90 ----
       <member><literal>NOT</></member>
      </simplelist>
  
!     <acronym>SQL</acronym> uses a three-valued logic system with true,
!     false, and <literal>null</>, which represents <quote>unknown</quote>.
!     Observe the following truth tables:
  
      <informaltable>
       <tgroup cols="4">