In XML parsers, validation is usually turned off by default because many XML authors are not writing constraints; leaving it off helps to avoid lengthy processing in production environments.

• 在XML语法分析器中,验证在缺省情况下通常关闭,这是因为很多XML作者都不编写约束;将其关闭可帮助避免产品环境中的冗长处理。