# [luatex] Glue node without spec field?

Taco Hoekwater taco at elvenkind.com
Thu Jan 7 13:10:08 CET 2010

```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).