In CWIS system, logical operator POR which has priority to logical operator AND can simplify the process of the logical expression and is easy to use.

• 在逻辑表达式中,创立POR这一特殊的运算符,既丰富了检索功能,又能简便地统一处理中英主题词互译,按照主题词属性关系查询等要求。