网上上是这么说的：
五、应邀赴华讲学、访问、经商，申请“F”访问签证者，需递交被授权单位的签证函电。申请半年、一年或两年多次入境“F”访问签证，还需提供：
1、被授权单位的签证函电原件；或
2、由中国主管部门核发的有效之营业执照复印件；或
3、与中国有经贸关系需经常来往中国之证明；
英文版：
for business "F" visa(single or multiple): A: an official invitation from the competent Chinese government agencies or organizations, or companies that are authorized to request the Consulate-General to issue visa; B: photocopies of business license issued by the competent Chinese agency or contracts for those who have business or investments in China.
请问：被授权单位的签证函电原件是怎样的东西？ 公司出具的一份证明和邀请函？
谢谢！
五、应邀赴华讲学、访问、经商，申请“F”访问签证者，需递交被授权单位的签证函电。申请半年、一年或两年多次入境“F”访问签证，还需提供：
1、被授权单位的签证函电原件；或
2、由中国主管部门核发的有效之营业执照复印件；或
3、与中国有经贸关系需经常来往中国之证明；
英文版：
for business "F" visa(single or multiple): A: an official invitation from the competent Chinese government agencies or organizations, or companies that are authorized to request the Consulate-General to issue visa; B: photocopies of business license issued by the competent Chinese agency or contracts for those who have business or investments in China.
请问：被授权单位的签证函电原件是怎样的东西？ 公司出具的一份证明和邀请函？
谢谢！