16. References

RFC 4648 cites US-ASCII, RFC 2119, earlier Base64 descriptions, MIME, PEM, and RFC 3548. These references provide the historical background and the normative keyword interpretation used by the specification.

Key references include:

• [RFC2119] Requirement keywords.
• [RFC3548] The earlier Base16, Base32, and Base64 Data Encodings specification, obsoleted by RFC 4648.
• MIME and PEM documents, which explain historical line wrapping rules.