LATEST UPDATE ON SP STACK PLANNING FOR XSS

The selection of a target version/stack is technically a consulting issue, as sometimes it can depend on customer requirements
That said, SAP may have recommendations that should be observed which may ensure compatibility – these however should be built into the SAP software logistics tools used to install, upgrade and patch the system

Historically the Wiki area  http://wiki.sdn.sap.com/wiki/display/ERPHCM/HOW+TO+GET+RID+OF+SP+STACK+MISMATCH+ISSUES (now found at http://wiki.sdn.sap.com/wiki/x/AwAqBQ) was provided to make correlations between component versions and SP levels more readable and indicate a best practice approach based on Release Notes, equivalency levels and the historical patching strategy of ESS/MSS landscapes

There are however more landscape possibilities than can be documented in the existing Wiki matrix or indeed in general - these have been made possible
by the EHP switch framework – customers seeking alternative landscapes to the ones documented in the SP Stack Mis-Match Wiki area
should go to www.service.sap.com/erp-ehp for documentation and assistance

In terms of landscape possibilities EHP5 also offers even more landscape possibilities that cannot be documented in a readable way in the current SP Stack Wiki matrix

In addition to new and existing landscape possibilities there is also a new approach to SP release strategy for certain software components and dependencies
In the past an SP may have been released purely to ensure numerical equivalence to the stack – you can see this where the byte size of 2 different consecutive SPs is the same
Recently SPs may no longer observe the equivalency levels documented in Release Notes – that is an SP may only be produced or necessary if a fix is produced
XSS Development have indicated that logically in patching, say the latest stack, the latest available SP to the equivalency level should be observed in cases where there is no equivalent SP available/released for that component in the required equivalency level. An example of this is BP Common Parts 1.41 for EHP4 stack 8 where SP7 patch 1 was recomended (instead of SP8) or ERP2004 SPS23 where SAP_ESS SP22 was recommended (instead of SP23). ** IMPORTANT TO NOTE -  I am awaiting update as to whether this is a permanent or temporary change to SP release strategy or affects only some components as I have noticed some recent SPs being released which are the same byte size for example BP ESS 1.41 SP8 and SP9 **
In light of the existing EHP options and more recent changes it is strongly recommended to use SAP software logistics tool when selecting and planning a stack
As per www.service.sap.com/sp-stacks which originally launched the stack concept, it mentions
                                                                        
"Implementation and maintenance of SAP enhancement packages for SAP ERP 6.0 is available only via SAP Solution Manager's Maintenance Optimizer  (MOPZ)."