How are US amateurs restricted in segments of bands where the Amateur Radio Service is secondary?
U.S. amateurs may find non-amateur stations in those segments, and must avoid interfering with them✓Bonne réponse
U.S. amateurs must give foreign amateur stations priority in those segments
International communications are not permitted in those segments
Digital transmissions are not permitted in those segments
Explication
A secondary allocation means other services hold the primary right in that spectrum, so amateurs must not cause harmful interference and must accept it. It is not a restriction on who you may talk to or what mode you may use.