What do the ABAP system variables SY-SUBRC and SY-DBCNT report?

What are core data services (CDS), and why do they benefit S/4HANA?

What must happen before an ABAP program can run, and what does it produce?

Why is cloning the worst way to change SAP functionality, and what detects clones?

What was the first method to enhance standard functionality without changing SAP objects, and how does it work for ABAP code?

What are Business Add-Ins (BAdIs), and what improved with 'new' BAdIs over 'classic' ones?

What is a transparent table, and what table types are gone in S/4HANA?