Read IfModifiedSince on a request with a MethodType of mtGet to determine whether the request is conditional. If the information requested by the Web client was not modified since the time indicated by IfModifiedSince, the response should be a not modified error rather than the information indicated by the URL property. 

The value of IfModifiedSince is given according to the local clock, not the clock of the Web client.

IfModifiedSince is represented using the TDateTime type. The integral part of a TDateTime value is the number of days that have passed since Dec. 30, 1899. The fractional part of a TDateTime value is the fraction of a 24-hour day that has elapsed. 

 

Expires 

Date 

Properties That Describe the Expected Response