Being phased out but still present in many modules.
Registering tables, sequences, and concurrent programs in the "Application Object Library" (AOL).
The R12 file system changed significantly from 11i. It now features a dual file system (fs1 and fs2) to support (introduced in R12.2). $APPL_TOP: Contains the product directories and files. Oracle Apps R12 Technical Tutorial Pdf
Creating validation rules for report parameters.
If you are looking for deep-dive tutorials, focus on these official Oracle documentation categories: Being phased out but still present in many modules
Manages the business logic and tech stack.
Stores all enterprise data in an Oracle Database. 📂 Key Technical Components Oracle Apps R12 Technical Tutorial Pdf
Are you focusing on or the newer R12.2 (Online Patching) ?