From manual:
block=tag/ By adding character / at the end of the tag's name, TBS won't retrieve the closing tag. The block will be defined on the single opening XML/HTML tag which contains the TBS tag. This can be useful to multiply an image for example.
My example:
<img src="test.png">[onshow;block=img/;when [some_var]='some_value']
Got error:
TinyButStrong Error in block's definition [onshow...]: at least one tag corresponding to img/ is not found. Check opening tags, closing tags and embedding levels.
Why its not working?