Skills taxonomy: multi layered???

Summary:

Looking to see if the Oracle community has implemented a skills library/taxonomy that is multi layered.

This is not specifically around attained proficiency levels eg basic, intermediate, high etc (although still interested)

This is more around a reporting structure very reminiscent of a finance chart of account that has grandparent, parent and child values.

Not only does this allow effective searching as a user, it also allows effective aggregating when reporting.

Example being:

Grateful to understand if other skills users have typically implemented the skills library showing the 'Skill title' (as above) and used reporting to support any aggregating. However, if using the titles as the searchable term without any subsequent relationship to the previous columns how a user could view all core skills in a single search?