1# note: this might be incomplete, mostly an example
2root        ::= en-char+ ([ \t\n] en-char+)*
3en-char     ::= letter | digit | punctuation
4letter      ::= [a-zA-Z]
5digit       ::= [0-9]
6punctuation ::= [!"#$%&'()*+,-./:;<=>?@[\\\]^_`{|}~]