Huh? From RFC1123:

<quote>

2.1 Host Names and Numbers

      The syntax of a legal Internet host name was specified in RFC-952 [DNS:4].  One aspect of host name syntax is hereby changed: the restriction on the first character is relaxed to allow either a letter or a digit.  Host software MUST support this more liberal syntax.

</quote>

It's from 1989. ICANN was founded in 1998.