Could anybody explain step by step why such arguments ( `NULL` pointer(s) ) when calling `pthread_create` like this:

```
pthread_create(&id_thread1,NULL,thread1,NULL);

```

result in default attributes for the `thread1` ?

I know that `pthread.h` file is a key factor here.
But unfortunately I do not understand why; the code is way too sophisticated to me.

Thanks in advance!