How to display a general list of products in a category including subcategories in xls template?

Question

XSL & XSLT

Good afternoon, I decided to try to create an online store on Umi. Decided to use the xlst template view. I ran into the problem that I could not find information in the documentation on how to also display products from subcategories in a category.
For example:
In category "A" there is category "B", in category "B" there is category "C", in category "C" there are two products for example "Fireboxes 1" and "Fireboxes 2". It is necessary to implement the output of goods for all branches of categories, and not only in the final one, that is, these goods will be in the general list of categories "A, B, C" Tell me how to implement this.