A space should be used wherever there is an intentional space left on the support: i.e. a space that never contained text (vacat). To express uncertainty as to whether or not a vacat is actually present, a <certainty> element with a match corresponding to the parent element (i.e. the gap element) should be given a locus with a value of "name".
‘(vac.?)’Silvio Panciera XI.3Josh Sosin