Hope you are all good.
We are doing ATC and we are kinda stuck with some tables that do not exist on classic SAP, like ACDOCA. In my example, the ATC is pointing to a select on BSEG and I do understand that it is replaced by ACDOCA but I'm thinking if there is a Sample system where I can see the tables filled, play with the data to check how it actually works. The point is that we need to do some of the ATC BEFORE we can start playing with the data, so here is where we are stuck.
Hopefully, SAP thought about that and set up a SAmple system with mock-up data?
please refer to SAP note 2041140 for how to obtain a SAP S/4HANA (On Premise) demo / trial system.
This is probably the easiest way to see how a SAP S/4HANA system behaves concerning FI processes and BSEG/ACDOCA tables, if you don't have an own SAP S/4HANA system yet.
The trial system can either be installed locally (On Premise) or via SAP Cloud Appliance Library ( see https://blogs.sap.com/2022/02/22/sap-s-4hana-offerings-in-sap-cloud-appliance-library/ )
For getting first hand feel and experience of hiccups & issues during ECC to S/4HANA, SAP strongly recommends to perform a PoC conversion preferably with copy of your ECC PRD system (SBX). Issues and fixes for them depends upon your source ECC system preparation and readiness for conversion. Details are provided in SAP S/4HANA conversion guides.
Regarding ACDOCA and other FIN tables, you might be aware, one needs to run FIN data conversion IMG activities like FIN customizing & FIN data migration as part of post processing (post Technical Conversion) to have data in those FIN tables.
I believe, ECC Sandbox (copy of PRD) conversion to S/4HANA will enlighten & enable you to plan & execute the complete SAP ECC landscape conversion.
Hope it helps. Good Luck.