PQnotifies and freeing memory.

After reading the below struct and free statement, I am rather confused..

Do I need to free the struct, the char *, or both?

Thanks.

PGnotify* PQnotifies(PGconn *conn);

 typedef struct pgNotify {
     char *relname;              /* name of relation containing data */
     int  be_pid;                /* process id of backend */
 } PGnotify;

 After processing a PGnotify object returned by PQnotifies, be sure to free it
with free() to avoid a memory leak.