mapcss concat() and cond()

[Polyglot]

This works:

text: rcn_ref;
or:
text: tag(rcn_ref);

When the name tag is present, this also works:

text: concat(tag(rcn_ref), " ", tag(name));

Without a name tag, no text is shown, though.

So I tried this:

text: name?rcn_ref:concat(tag(rcn_ref), " ", tag(name));

and this:

text: cond(name,rcn_ref,concat(tag(rcn_ref), " ", tag(name)));

Would it be possible to simply add a blank string in concat() if the tag is not available.

That would be the most intuitive.

Polyglot