info-xref-xfile-alist

info-xref-xfile-alist is a variable defined in `info-xref.el'.
Its value is

nil

Documentation:
Info files found or not found, during info-xref processing.
Key is "(foo)" etc and value nil or t according to whether info
manual "(foo)" exists or not. This is used to suppress
duplicate messages about foo not being available. (Duplicates
within one top-level file that is.)