What value should be initialized in hints parameter of getaddrinfo()?

Question

In the hints parameter of getaddrinfo(), there is a pointer to the addrinfo struct, but what value should I initialize in the addrinfo object? In the addrinfo struct, there are several values that can be set, but in many resources there are 3 types of information that must be init in the example below:

struct addrinfo address_info = {
   .ai_family;
   .ai_socktype;
   .ai_flag;
};

Is there any other value that needs to be set?