[NTG-context] weird issue with xtable

[Taco Hoekwater]

> On 13 Aug 2020, at 14:15, Pablo Rodriguez <oinos at gmx.es> wrote:
> 
>>> My questions are: what is the restricted horizontal mode (as different
>>> from the horizontal mode)?

I forgot to answer this. Simple explanation:

* 'restricted horizontal mode' is inside an \hbox{} or something similar like a header/footer, 
  where line breaks are forbidden
* ‘horizontal mode’ is inside a paragraph, where line breaks are possible

But the ‘restricted’ part is not relevant to your problem, \prevdepth is forbidden in horizontal mode  regardless of restrictions; it is only allowed in vertical mode.


Somehow your table ends up being typeset in a horizontal context, based on the error message (at least, if we assume that the error message was triggered by a table). 

But why that is? I do not have any other good ideas. And unfortunately lots of different things in ConTeXt can trigger an implicit horizontal context. 

For debugging, you could try adding this to the preamble (or grouped around each xtable, for slightly less damage to the vertical spacing):

  \let\prevdepth\relax
  \newdimen\prevdepth 

that should at least remove the error report.  The vertical spacing in the pdf output will be wrong (!!!), but perhaps the output can provide a clue about what triggered the problem.

Best wishes,
Taco