The other day in class we were looking at Luke 23 and a student mentioned that v34a was not present in all the manuscripts. Good for her, I thought - even first years need to get their heads into such issues. Then I took a look at my NA27 and found the apparatus a little confusing, I think because it uses the term txt in the apparatus for witnesses supporting the reading of v34a, BUT this is not really the txt because it is enclosed in double square brackets - meaning that the editors DO NOT think it is the text of Luke. The NA27 txt is to omit the half verse.
I had a quick look at some other double square bracketed passages (Luke 22.43f; John 7.53-8.11; Mark 16.9-20) and these are treated quite differently, and a little more clearly. The double square brackets themselves form the link to the apparatus (in Luke 23.34 it is the little square); and then we are given the witnesses which don't have the passage and those which do (none are designated as txt).
I suppose Luke 23.34 may have been treated a little differently because it is only half a verse; but my modest recommendation would be that this is revised in NA28 so that txt is not used in such a confusing way.
Someone with a computerised-thingy could probably identify all the double square brackets in NA27 and see whether Luke 23.34 is alone in this treatment.