For instance a programmer must check why a function returns the negative value. He may read the source code and "execute" it similar to the computer. He may use debugger and consider the results of execution of each code statement step by step. He may make a prototype to simulate the behaviour of the program component. He may insert into code the output of information he need and read the log file.
The computer-level information can be received in different ways. It may be simple or complex to get. This process may be error prone and expensive. Only the clearness of it is important for us yet.
If the process of information search is correct, the result is determined. We may say that the computer-level is as clear as the compiler-level.