All right, I've found a tentative solution that appears to work in all cases, but I'd like to know more about why the code I'm patching was implemented in the first place, because I don't want to break anything else. According to the code in page-pcl.mkiv, the \stoppagecolumns macro has two implementations, \page_col_stop_yes and \page_col_stop_nop. The choice of which implementation is used is determined by which of two implementations of \startpagecolumns (\page_col_start_yes and \page_col_start_nop) is used. That choice, in turn, is made in the \page_col_start macro, in the following lines:

```
\c_page_col_n_of_columns\pagecolumnsparameter\c!n\relax
   \ifnum\c_page_col_n_of_columns>\plusone
     \expandafter\page_col_start_yes
   \else
     \expandafter\page_col_start_nop
   \fi
```

so if the number of columns (i.e., the n option for the pagecolumns environment) is more than one, the "yes" implementation of the start and stop commands is used.

But this seems wrong. The naming convention for the two implementations ("yes" and "nop") suggests that they should be related the parameters "page=yes" and "page=no" (hence, no page, which is what I think "nop" abbreviates), but the choice of which implementation to use is determined not by the page parameter, but by the n parameter. Is this an error in the code, or am I just understanding this incorrectly? Is there some reason why a layout with more than one column would need special instructions to add a blank page after stopping the environment?

In any event, I was able to solve the problem by patching the \page_col_start_yes macro to invoke the \page_col_start_nop macro as follows:

```

\unprotect

\def\page_col_stop_yes

{\page_col_stop_nop}

\protect

```

With this fix, the MWE I provided works regardless of which column the text ends in. I'm content to consider the problem solved, but I would certainly appreciate any feedback on my thoughts and questions about page-pcl.mkiv.

Joey

On Thu, May 14, 2020 at 5:03 PM Joey McCollum <jmccollum20140511@gmail.com> wrote:
Okay, I think I'm getting close, but I'm not quite there yet. The pagecolumns source code is found in page-pcl.mkiv (source.contextgarden.net/tex/context/base/mkiv/page-pcl.mkiv), and in that code, the \page_col_stop_yes macro seems to have something to do with the issue:

```
\unexpanded\def\page_col_stop_yes
  {\column % \page_otr_eject_page
   \page
   \endgroup
 % \setupoutputroutine[\s!singlecolumn]%
   \page_otr_command_set_vsize
   \page_otr_command_set_hsize
   \page
   \endgroup}
```

If I redefine this macro in my MWE as follows, I can remove the extra page that is added when the last page ends with text in the last column:

```

\unprotect

\def\page_col_stop_yes

{\column %\page_otr_eject_page

%\page

\endgroup

% \setupoutputroutine[\s!singlecolumn]%

\page_otr_command_set_vsize

\page_otr_command_set_hsize

%\page

\endgroup}

\protect

```

Commenting out the \page calls does the trick in this case, but now, if the last page ends with its text in a column before the last one, then the last page is not typeset at all, and a blank page takes its place.

On Sun, May 10, 2020 at 8:34 PM Thangalin <thangalin@gmail.com> wrote:
Bump.

See also: https://tex.stackexchange.com/q/542993/2148

On Mon, May 4, 2020 at 11:46 AM Joey McCollum
<jmccollum20140511@gmail.com> wrote:
>
> After continuing to look into this a bit, I noticed that a similar issue involving the insertion of a blank page after a columnset environment has been discussed on the mailing list in the thread "Blank page inserted when text reaches column's end" (dated 08 Dec 2019). In that thread, a proposed solution was to redefine the \page_grd_stop macro found in page-cst.mkiv as follows:
>
> ```
> \unprotect
> \def\page_grd_stop{%
>   \endgraf % needed, else wrong vsize in one par case
>   \vfill % otherwise weird \placenotes[endnotes]
>   \page_grd_command_set_vsize % needed
>   \penalty\c_page_otr_eject_penalty
>   %\page_grd_command_flush_page
>   \page_otr_fill_and_eject_page
>   \page_grd_command_set_vsize % why here
>   \egroup
>   \page_otr_command_set_vsize
>   \page_otr_command_set_hsize
> }
> \protect
> ```
>
> Unfortunately, this approach was found to have potential issues in that thread, and it does not fix the problem with pagecolumns in my MWE. Are pagecolumns commands aliased to pagegrid commands like columnset commands are, or are they defined somewhere else? I checked page-col.mkiv, but it seems to be too short to be the file that defines pagecolumns behavior.
>
> Joey
>
> On Sat, May 2, 2020 at 11:46 AM Joey McCollum <jmccollum20140511@gmail.com> wrote:
>>
>> I recently found the pagecolumns manual (http://www.pragma-ade.com/general/manuals/pagecolumns.pdf), and in several of the examples (including those for side floats and footnotes), the addition of a blank page after the end of the pagecolumns environment also seems to occur. So when the manual says, "We always start at a new page and end on a new one," does it mean that this is a feature of pagecolumns? And if so, is there any way to disable it? I have no problem with a page break after the end of the pagecolumns environment, but an empty page added after the break seems unnecessary. I checked for a wiki page on the \definepagecolumns command to get more information on its accepted inputs, but there doesn't appear to be a page for this command.
>>
>> Joey
>>
>> On Tue, Apr 28, 2020 at 1:40 PM Joey McCollum <jmccollum20140511@gmail.com> wrote:
>>>
>>> I am typesetting a document using pagecolumns to ensure that my footnotes are set ragged-bottom in columns. I have observed some unexpected behavior whenever the last column on a page is left incomplete: a blank page is added at the end of the document. A minimal working example follows:
>>>
>>> ```
>>>
>>> \starttext
>>>
>>> \startpagecolumns[n=2]
>>>
>>> \dorecurse{3}{\par\input zapf}
>>>
>>> \stoppagecolumns
>>>
>>> \stoptext
>>>
>>> ```
>>>
>>> I typeset this using ConTeXt version 2020.03.10, as released with TeXLive 2020. Notably, if \dorecurse{3} is changed to \dorecurse{2} or \dorecurse{6} (so that the text ends in the first column of a page), then there is no problem. I have tried to fix this by specifying page=no in the \startpagecolumns arguments, but it did not change anything. Is there something else I am missing?
>>>
>>> Thank you,
>>>
>>> Joey
>
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