+2  A: 
  • One bar: whitespace can be inserted between pairs of tokens.
  • Two bars: no whitespace allowed between pairs of tokens.
Peter
Hmm. What about the array image? (http://json.org/array.gif) There is WS allowed in that (around '[', ',', and ']') but it doesn't seem to be noted. And two string tokens never occur together...
Thanatos
@Thanatos I don't understand your question: the array image has single bars at each end, which shows whitespace is indeed allowed, as (I think) you're also saying?
Peter
Oh. Hmm. While I did misread that, I still don't quite get it. These are both valid JSON: `[ [ 1 , 2 ] ]` and `[ "hi there" , "more space?" ]`
Thanatos
@Thanatos: yes. The single bars on array indicate that the whitespace between your brackets, numbers and strings is allowed.
Peter
@Peter - Thanks. At the bottom of the page, there is a statement: "Whitespace can be inserted between any pair of tokens". Perhaps that should be amended?
Steve
A: 

Single bars denote an element that is a "first-class" element (e.g. object, value), double bars delimit an element that is a subcomponent of another.

Jen