Sieve - ABNF of block

I believe a block cannot contain -just- comments or be empty, like this:

... { 
    # commented for now
    # discard;
}

but this might be the intention. If not, these rules prevent this:

block = "{" commands "}"
commands  = *([WSP] command [WSP])
command = identifier ...

Maybe
commands = *[WSP] *([WSP] command [WSP])
although this does not really reprsent commands.

- Wilbert