Re-definition of Field Classification by Hierarchy

This paper proposes a re-definition of field classification based on hierarchical levels $K_0$--$K_4$. The framework is presented as a provisional and incomplete starting point, rather than a fixed taxonomy. Each field may require different depths of hierarchy, and cross-level or cross-domain connections are not restricted. The purpose of this work is not to finalize a universal classification, but to open a structure through which specialists in each domain can reconsider and reorganize their own field. Any disagreement with the proposed allocation is welcome; if a field naturally crosses levels or connects to others, such movements should be accepted rather than suppressed. This study aims to initiate discussion, not to close it.