By creating alternative ways of handling a command if an element is not supported, forward-processing guarantees that the code used is relatively robust and insensitive to differences in parser conformity.

• 如果不支持某个元素,通过创建备用的命令处理方法,前向处理可以保证所使用的代码相对可靠,并且对分析器一致性方面的差别不敏感。