luigi scarso wrote:
If I understand it correctly, if subtype is not 0 then spec is an empty node
No, that is wrong. spec is *never* an empty node. The spec can be zero though, and that is a static spec with values 0pt plus 0pt minus 0pt. The lua interface treated that wrongly (all other node links cannot be zero, and there was no special case for spec fields). The non-zero subtype means that this glue matches one of the internal parameters, e.g. 9 == \rightskip, or that it is a leader (values 100-102).
n.leader == nil
Yes, in this case the leader is nil, leader only has useful values for glues with a subtype that says it is a leader. Best wishes, Taco
