Nobuyoshi Nakada wrote:
> Hi,
> 
> At Fri, 20 Feb 2009 20:49:35 +0900,
> Urabe Shyouhei wrote in [ruby-core:22289]:
>> What do you mean here in "official"? because AFAIK there has been no single
>> line of official syntax definitions so far.
> 
> Matz's book and official tutorial[1] mention about "then" but
> not ":".  Is there any description about such colons?

At least O'Reilly's "Programming Language Ruby" has a detailed description
about it.  One of a Matz's book no wonder.