A periodical issued under a continuing title at regular intervals — even if it resembles a book in format — is classified under 4902 rather than 4901. The key indicators are a recurring publication schedule, volume/issue numbering, and an ISSN rather than an ISBN. A one-time special edition bound like a book but issued as part of a serial may still qualify as a periodical.

HTS classification applies to physical goods crossing the border. Digital or electronic editions transmitted electronically are not classified under 4902 and are generally outside the scope of the tariff schedule. Only physical printed copies imported into the US require an HTS classification.