response 9 of 15:

May 9 08:04 UTC 2018

I see from resp:8 that the tags can appear anywhere in a line with or 
without other text.

response 11 of 15:

May 9 08:07 UTC 2018

Trial and error: item:agora,1

response 13 of 15:

May 9 08:10 UTC 2018

resp:11 and resp:12 work! 

I got my wishes!

response 15 of 15:

May 9 09:12 UTC 2018

I poked around the bt source and it looks like "conf:", "item:", and
"resp:"  and "resp:" are the only supported internal link tags. bt
actually processes th processes them as types of URLs.

To summarize the syntax ...

  conf:<conference>

  item:[<conference>,]<item#>

  resp:[[<conference>,]<item#>,]<response#>

<conference> and <item#> default to conference and item of the post in
wh which the tag appears.

",", ".", ":" or a mixture of the three can be used to separate the 
conference, item, and response parameters of the tag.