비교할 수없는 Michelson 쌍

다음 Michelson 스크립트를 입력하려고하면 유형 오류가 발생합니다.

 parameter unit;
storage (big_map (pair string address) (list timestamp));
code {CDR; NIL operation; PAIR};
 

 Ill formed type.
At line 2 characters 17 to 37,
comparable type expected.Type pair string address is not comparable.
 

Michelson 참조 에 따르면 pair ty1 ty2,address 및 string은 비슷합니다.내가 뭔가를 놓치고 있습니까?이 문제를 피할 수있는 방법이 있습니까?

When I try to type the following Michelson script, I get a type error.

parameter unit;
storage (big_map (pair string address) (list timestamp));
code {CDR; NIL operation; PAIR};

Ill formed type.
At line 2 characters 17 to 37,
comparable type expected.Type pair string address is not comparable.

According to the Michelson reference, types pair ty1 ty2, address, and string are comparable. Am I missing something? Is there are way to circumvent this issue?