I am still trying to determine what you want (perhaps my problem). The original question in thread related to a special case where the field may contain whitespace. Is that what you are asking for?
So let us return you your question
If exclude the white space issue
That is if in a tiddler tagged $:/tags/ViewTemplate
<$list filter="[all[current]!has:field[section-type]] :else[{!!section-type}is[blank]]">
No section-type
</$list>
- The first part of the filter is true if there is no section-type even empty, we say “No section-type”.
- If the first is not true ELSE then “section-type” contains something
- but we test if its blank and if so we say , we also say “No section-type”.
- If there is a chance of whitespace other than blank/spaces we can add trim as before.
[all[current]!has:field[section-type]] :else[{!!section-type}trim[]is[blank]]
Is this what you want @JanJo ?