Program conversion is not required if upgrading to IBM i 7.1 from IBM i 6.1.
If upgrading to IBM i 7.1 from IBM i 5.4 or any previous release, program conversion is required for all programs that use the IBM i Machine Interface (MI). This conversion upgrades and refreshes programs to take advantage of the latest system enhancements, including enhanced system integrity, improved performance, and a range of new operating system and processor capabilities.
In order for a program to be converted, its creation data (sometimes referred to as observability) must be available. Programs created for IBM i V5R1 or later automatically retain creation data sufficient for conversion. Clients and ISVs with programs created for OS/400® V4R5 and earlier need to ensure that creation data is available for the conversion process.
IBM has provided the Analyze Object Conversion (ANZOBJCVN) tool for IBM i 5.3 and 5.4 (i5/OS V5R3 and V5R4) to help you plan for program conversion. This tool helps you identify potential conversion difficulties, if any, and estimates the time required for program conversion. Looking for additional information on program conversion? Checkout the ITSO Redpaper IBM i Program Conversion: Getting ready for IBM i 6.1.IBM i Program Conversion: Getting Ready for 6.1 and Beyond (Redpaper)