RFC 2109 predates anything that vaguely resembles PHP, and Netscape (thus, defacto, basically everyone using the internet), had cookies 3 years before the RFC. PHPSESSID wasn't added until PHP 4 in 2000.
If you're going to be a bitchy pedant, you'd damn well better be CORRECT.
If you're going to be a bitchy pedant, you'd damn well better be CORRECT.