Nicolas Mondon schrieb am 19.09.2019 um 19:18:
>
> Thank you Wolfgang for your answer.
>
> So, yes the figures/tables should appear before the text on a even
> (left side) page while the text would appear only on odd (right side)
> pages. The left page should be empty when there are no figures/tables
> for the following right page, and the float doesn't have to appear
> strictly at the same vertical position as the reference, but as
> possible only. Specially beacause, it may have several references in
> only one paragraph for exemple on the right page, and so the figure
> should appear in the right order on the left page, but couldn't be
> exactly at the same height. Also, if there are too many references in
> on right page, the figures which can't fit the left page should go on
> the top od the next left page...
>
> It's possible that my answer change the proposition you made at the
> end of your message. Nevertherless, there is some thing in your last
> paragrph which is not clear for me : " Afterwards you split each page
> in half and create two separate pages from one single page which can
> be done with a loop (can be done theoretically with the imposition
> mechanism but a separate document is easier)."
>
Step 1:

  Create a document with a very big left margin where you can place all
floats.

\setuppapersize
   [A3,landscape]

\setuplayout
   [backspace=23.5cm,
    width=15cm,edge=14cm]

\showframe

\setupfloat
   [default=leftedge,
    minwidth=14cm]

\starttext

\input ward

\startplacefigure
\externalfigure[dummy]
\stopplacefigure

\input knuth

\startplacetable
   \starttabulate[|c|c|c|]
   \FL
   \NC A \NC B \NC C \NC\NR
   \ML
   \NC X \NC Y \NC Z \NC\NR
   \LL
   \stoptabulate
\stopplacetable

\input zapf

\stoptext


Step 2:

Split each page into two separate pages where one contains all floats
while the other page contains the text.

Wolfgang