Generally speaking, it will be divided into fields and directions according to the application code 1, with code 2 as the reference. As far as I know, some departments of the National Natural Science Foundation of China should use computer programs and manpower to classify applications and assign experts more accurately.

If the code 1 is inappropriate and the code 2 is accurate, it is a bit risky. If the application topic is the cross field of code 1 and 2, and it is also a subject, the risk is not great, because the relevant experts will understand the work. On the contrary, if the span between code 1 and code 2 is relatively large (refer to the application guide, which maps to all directions of the subject), the subject obviously does not belong to the category of code 1, which is a tragedy. Please read this guide carefully next year to understand the scope of application of this guideline.

Because I don't know your specific topic and direction, I can only say this in general. The best way is to directly consult the project leaders of the relevant departments of the Fund Committee. On the one hand, it is authoritative, and it does not rule out that he/she will pay attention to and consider your problems when appointing experts.