Taxonomies creation for 21C new feature "spend classification"

Summary:

We are trying to create taxonomies for spend classification. When you click on 'Download Categories' it downloads Purchasing taxonomy.csv file . This csv file contains columns : Taxonomy ,Category Id,Category Name and Category Description 

Our ask is what are the values that go into these columns ?? (all are required fields)

Taxonomy: here we believe it will be similar to the Name seen in the configuration page.so in this case it should be 'Purchasing taxonomy'

Category Id : from which ui/table do we pull this data ? is it from egp_categories_b or some other table/UI ??

Category Name : will the nomenclature here be just category OR category.subcategory ..from which ui/table do we pull this data ?