I always use the PDF version of the manuals.
You can then use your PDF reader's 'Find' function (Ctrl+F) to search a manual and easily find things, instead of relying on Yamaha's typically hopeless 'Index'

This often does not include the topic that you are looking for, even when there is adequate information in the manual! What do Yamaha expect customers to do? Read (and memorise) the whole manual from cover to cover!

That said, in this case 'Punch In/Out' is included the CVP Reference Manual index. However for the PSR3000, even though there is a similar section about 'Punch In/Out' in its Owner's Manual (starting on page 157), and the procedure is called the same, there is no entry for it in the so called 'Index'!
Regards
Ian