It is an unfair or deceptive act to use in any advertising an abbreviation which is confusing, misleading or not commonly understood by the general public (e.g., abbreviations commonly understood--AC, AM/FM, AUTO, AIR, 2DR, CYL, MSRP, DOC, and e.g., abbreviations not commonly understood--WAC, PEG) or approved by federal law or state law (e.g., terms allowed by the Federal Truth in Lending Act, 15 U.S.C. 1601 et seq., and the Consumer Leasing Act of 1976, 15 U.S.C. 1601, et seq., such as "APR").
Ill. Admin. Code tit. 14, § 475.250