[luatex] glue nodes

[Taco Hoekwater]

On 12/17/2012 04:32 PM, Herbert Voss wrote:
> Hi all,
>
> in the documentation I read:
>
>
> \subsubsection{glue_spec items}
> [...]
> \starttabulate[|lT|l|p|]
> [..]
> \NC writable      \NC boolean \NC If this is true, you can't assign to
>                    this \type{glue_spec} because it is one of the
>                    preallocated special cases. New in 0.52\NC\NR
>
>
> Is this correct that "writable=_true_" refers to a preallocated node?
>  From what I read it should be false??

Depends on what you mean by preallocated node. There are a few
glue_specs that are allocated by luatex's internal initialization,
for example the one that belongs to \z at skip:

    0pt plus 0pt minus 0pt

these are the ones that have writable==false (because they are
shared between nodes and parameters, and changing the value
would change all of them).

Best wishes,
Taco