How to add sub accounts to COA

Hello all,

I am trying out Dolibarr with version 15.0.1. I’m just starting to work with the COA to import an existing COA from our production system. I see that there are no provisions for sub accounts - or at least I cannot seem to find any. Is there a method to do this?

My account would be something like
1000
1000-100
1000-200
1000-300

The documents do not seem to cover this at all and the explanations provided in the sample import are ambiguous (in several respects).

Any help or direction would be appreciated!
Thank you,
Tim