Code 10/2 is a very general upbeat response. More detailed definitions of a good mood are given later in the code.
Note that code 10/2 is more than neutral. It is more than 'business as usual'. There is a definite 'happy' component.

The provision of codes 10/2, 10/3 and 10/4 is to allow a broad, general response to be given. If you wish you can just remember these three codes.

The use of 10/2 should at least be sincere. It should not just be the easiest way to respond to the question: 'What is your mood?'