How to Verify that the Payables Payment Program Uses This Seeded Package?

I have found previous discussions that assert:

"There is a standard package IBY_FD_EXTRACT_EXT_PUB which can be used to extend the XML Extract that is being generated by the Payment Program."

". . . which package I should use to add additional fields in the xml extract? I guess the package is IBY_FD_EXTRACT_EXT_PUB."

At this point, I'm certain that the XML Extracts for all payment types (including positive pay) use this package, IBY_FD_EXTRACT_EXT_PUB, but is there an admin guide or MOS doc that verifies this?