VS生成页面中的一段！是什么啊！

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<input type="hidden" name="__EVENTTARGET" id="__EVENTTARGET" value="" />

<input type="hidden" name="__EVENTARGUMENT" id="__EVENTARGUMENT" value="" />

<input type="hidden" name="__LASTFOCUS" id="__LASTFOCUS" value="" />

<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEPDwULLTEyMjQzMzg2NjAPZBYCAgMPZBYOAgkPDxYCHgRUZXh0ZWRkAhEPEA8WAh4HQ2hlY2tlZGdkZGRkAhMPEA8WAh8BaGRkZGQCFQ8QDxYCHwFnZGRkZAIXDxAPFgIfAWhkZGRkAh0PDxYCHwBlZGQCIQ8QDxYCHgdFbmFibGVkZ2QQFQMHQW5hbHlzdAhEZXNpZ25lcglEZXZlbG9wZXIVAwdBbmFseXN0CERlc2lnbmVyCURldmVsb3BlchQrAwNnZ2dkZBgBBR5fX0NvbnRyb2xzUmVxdWlyZVBvc3RCYWNrS2V5X18WBgUMd29ya2VyQnV0dG9uBQpib3NzQnV0dG9uBQpib3NzQnV0dG9uBQh2cEJ1dHRvbgUPcHJlc2lkZW50QnV0dG9uBQ9wcmVzaWRlbnRCdXR0b24os8ujAqp6uhAT6F36KuYF2CsLng==" />

</div>