THPDFDocumentHandlerStatus Type
THPDFDocumentHandlerStatus = (
dhsNotRun, dhsSucceeded, dhsNoHandler, dhsInvalidOptions,
dhsInvalidSource, dhsUnsupportedContent, dhsBudgetExceeded,
dhsCancelled, dhsHandlerFailed, dhsDestinationFailed
);區分識別、驗證、額度、取消、處理器與輸出目的地各種結果，預期中的失敗不必靠例外來表達