XML: Add timestamp (common settings)
At first you need to setup either TElFileTSPClient or TElHTTPTSPClient object as descreibed in this how-to article.
Then you would need either to assign this object to TElXAdESSigner.TSPClient property or pass it as a parameter to one of Add*Timestamp() methods (eg. AddSignatureTimestamp() method) of TElXAdESSigner.
TSPClient property tells the component that the same TSP client will be used for all timestamps. For example, if you create XAdES-X-L form (using TElXAdESSigner.Generate(XAdES-X-L) method), then SignatureTimestamp, SigAndRefsTimeStamp and RefsOnlyTimestamp would be created using the same TSP client. Additionally, you may set TElXAdESSigner.IgnoreTimestampFailure property, if you don't want signing to break, if timestamp operation fails.
The Add*Timestamp() methods can be called for TElXAdESVerifier object to add additional timestamps or extend XAdES form. For example, if XAdES form is XAdES-T, we can call AddSignatureTimestamp() method to add signature timestamp using a different TSP service. When Add*Timestamp() method of TElXAdESVerifier object is called, you should check the returned result: if it is 0, then the operation has succeeded, otherwise TSP error code value is returned.
In some rare cases you may need to adjust canonicalization method used by a timestamp. In this case you may use TimestampCanonicalizationMethod property of TElXAdESSigner and TElXAdESVerifier (default value is xcmCanon).