On Fri Sep 01 10:25:52 2017, ray wrote:
> On 01/09/2017 02:49, Mark Andrews via RT wrote:
> > 
> > Is a empty media blob allowed 
> 
> It's not explicitly prohibited in the draft at the moment
> 
> > and if so how is is represented in presentation format? 
> 
> On my CLI base64 decoder the string "=" is accepted as a legal
> representation of an empty string.

The base64 program which is part of GNU coreutils treats "=" as invalid
input.  And I believe it is the right thing to do as section 10 ("Test
Vectors") of RFC 4648 contains:

    BASE64("") = ""