I am confused - why do I need to activate Profit Center Accounting functionality in SAP S/4 1709?

We recently upgraded a test system from S/4 1610 to S/4 1709 and one of the interesting things that we found was that SAP is recommending that the switch for activating profit center accounting in Controlling should be activated. This was a bit of a surprise because I found no mention of this in the Simplification document for 1709 or in any on-line searches.

Ever since release ECC 5.0 clients using the new general ledger with the profit center or segment scenarios active were warned against activation of classic PCA. With the new GL scenarios profit center functionality was incorporated in the GL and the old profit center ledger 8A was not activated. In this case the classic reports in the information system for PCA would not return any results if they were executed.

 For example, the old profit center line item report KE5Z when run in our 1610 system gives no results

Also, any of the old report painter based reports also return no data as they are reading from libraries based on the 8A ledger.

For example, report S_ALR_87013326 - Profit Center Group: Plan/Actual/Variance would return:

This is expected behaviour since PCA is not active in the Controlling Area.

After our upgrade we were testing plant maintenance orders and started getting errors on cost calculation related to profit center accounting.

The 415 message states

"FI-GL (new)" scen. FIN_PCA used in ldgr 0L; activate PrCtr Acctng in COAr 1000

Message no. FINS_ACDOC_CUST415

Diagnosis

The FI-GL (new) scenario FIN_PCA is assigned to ledger 0L in table FINSC_LEDGER_SCEN.

System Response

A consequence of these table entries is that the system regards Profit Center Accounting as active.

The FI-GL (new) scenarios are obsolete: In S/4HANA there is no IMG acitivity available for maintaining scenarios. However, the system still evaluates these obsolete Customizing settings. In order to make it transparent for users that Proft Center Accounting is active, please activate Profit Center Accounting:

Procedure

For controlling area 1000, activate Profit Center Accounting in the fiscal-year dependent settings of the controlling area.

Because the FI-GL (new) scenarios were neither time-dependent nor fiscal year-dependent, please activate Profit Center Accounting for all fiscal years.

Note that activating Profit Center Accounting does not automatically activate the "old" profit center ledger 8A. Activating profit center ledger 8A is not mandatory.

This seems to indicate that we should now activate profit center accounting in conjunction with using the New GL scenarios. The first link from the message takes you to 0KE5 where I activated PCA in the controlling area (see below) it seems that the check box for PCA activation has been removed from the control indicators in OKKP.

After this change we are able to cost and release the PM order. Now when we make postings we are generating an additional document.

This one occurred on the MIGO to the order but we also got one on settlement as well.

Out of curiosity I ran the old profit center line reports and information system reports and:

The report is stating ledger 8A and the fields are referencing table GLPCA which also shows ledger 8A.

The other report painter reports also work and return values.

I was confused by this so went back to the message and followed the link for Activating profit center ledger 8A is not mandatory. This takes us to 1KEF where I believe the idea is to deactivate updates to PCA.

I also had to deactivate the following error messages:

Now when I process the transactions I get no PCA documents and no ledger 8A updates

So at the end of the day the system is working but I have been unable to find any documentation on this change or why is it necessary.