Is Lightning Source’s Paper Stock NISO Compliant?

Recently I was filling out the form on the Library of Congress’s website for an LCCN and noticed a question regarding “Permanent Paper.” I did some research to see if any of my books are printed on such paper and found I couldn’t figure out if Lightning Source’s paper met the standard. So I contacted Lightning Source and found out that, while its paper is acid-free, it does not meet the standards for Permanent Paper that the check box on the LCCN request form indicates.