我某公司于9月8日收到美国A公司就出售化工产品(AA)发来的电文: “OFFER COMMODITY AA ART.101 5000M/T IN BULK USD 3500 PER M/T FOB NEW YORK NOV.SHIPMENT BY IRREVOCABLE LETTER OF CREDIT PAYABLE AT SIGHT PLEASE REPLY REACHING US SEPT.12TH.” 我方接电后,经研究,于9月11日上午10时去电如下: “YOURS 8TH ACCEPT PLEASE SEND YOUR CONTRACT IMMEDIATELY.” 当天上午11点,我公司业务员收到A公司电文如下: “WE HAVE RECEIVED YOUR FAX JUST NOW BUT WE ARE VERY SORRY THAT OUR OFFER HAS BEEN REVOKED BECAUSE THE DEMAND IS BRISK AND THE GOODS HAS SOLD OUT.” 试分析上述电文,并指出双方是否成立了合同关系。为什么?
认证机构采用的安全系统应当满足的目标有()。
[A]确认数据电文的归属
[B]保证数据电文完整
[C]合理地避免被侵入和人为破坏
[D]合理的安全程序