"Supplemental information" refers to extra details or additional data that is provided alongside something to give more context or explain it further. Full definition
Your broker may provide supplemental information about when you bought the older shares and the amount you paid. (fairmark.com)
These pages are intended primarily to serve as supplemental information for our clients to help them understand why we recommend what we do and to explain what can be expected after a specific diagnosis. (nccat.com)
You may read through that link for supplemental information on which exchange your preferences may be suited. (finder.com)