在Web Application中制订错误信息列表，有必要为每个错误建立一个错误号吗？

可以参考TFS中的错误信息定义

http://msdn2.microsoft.com/en-US/library/aa337645(VS.80).aspx
Visual Studio Team System 
Error and Event Messages in Team Foundation 

Team Foundation displays error and event messages to inform you of successful and unsuccessful operations. A subset of the error and event messages have been assigned unique ID numbers in the form TFnnnnn.

Numbered Error and Event Messages

TF10001: The Team Foundation Server name is not present in configuration file. Contact your Team Foundation Server administrator.
TF10002: Source control is unable to determine the SID for user name: {0}.
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