Functional Impact Document - 12.1.3 Consolidations - CS Cumulative Patches (Doc ID 1608427.1)
On a regular basis Oracle Development issue cumulative patches for the Core Service product. For EBS Release 12.1.3 they provide documentation to identify the impacted flows / testing recommendations, and additional set-up details required for testing the bug fixes delivered in the Core Service cumulative patches.
These 'Functional Impact Assessments' (FIA) can be accessed from Doc Id 1608427.1.
If you are considering applying a roll up patch it would be worth reviewing the relevant FIA.