Thank you Alan. Yes, I have seen the possibility of generating automatically the labels but unfortunately the problem remains when you move the subfigure. In the meantime, I have tried this:

\startplacefigure [number=no]
\startcombination [nx=3]
{figure 1} {\incrementcounter[figure]\textreference[pic1]{\getnumber[figure]}\in[pic1]}
{figure 2} {...similar...}
{figure 3} {...similar...}
\stopcombination
\stopplacefigure

and then
\in[pic1]
in the body of the text, which looked very promising; the trouble is that for some reason that i do not understand, the \in[pic1] in the label of the picture works ok, but anywhere else in the text, either before of after the placefigure environment, it generates a reference to the last picture produced, that is pic3 after and pic0, say, before. I though it was aproblem of expanding the figure counter and added \expanded either before \getnumber of \textreference, but with no luck...
Luca
On Jul 30 2019, at 4:52 pm, Alan Braslau <braslau.list@comcast.net> wrote:
> On Tue, 30 Jul 2019 11:20:03 +0200
> Luca Mauri <luca.mauri@gmx.com> wrote:
>
> > I am trying to typeset two or more figures next to each other, inside a floating environment, each with its own label. I am familiar with a mechanism of the form
> > \startplacefigure[reference=pic]
> > \startcombination[3*1]
> > {figure 1}{a}
> > {figure 2}{b}
> > {figure 3}{c}
> > \stopcombination
> > \stopplacefigure
>
>
> This does not answer your question, but do you know about:
> \startplacefigure
> \startcombination [nx=3,alternative=label]
> {figure 1}
> {figure 2}
> {figure 3}
> \stopcombination
> \stopplacefigure
>
> Alan