I have found this, that works, buy I don't know if there's a possibility of using less code: % !TEX encoding = UTF-8 Unicode % !TEX TS-program = ConTeXt-MkIV % questo codice centra il blocco dei versi sulla pagina \defineframedtext [poemframed] [width=\textwidth, autowidth=force, align=flushleft, before=, after=, frame=off] \definenarrower[poemnarrower] \definelines [poemlines] [before={\startpoemnarrower[left]}, after=\stoppoemnarrower] \definebuffer[poem] \def\stoppoem{\setups{poems:buffer}} \startsetups poems:buffer \setupnarrower[poemnarrower][left=0pt] \setbox\scratchbox\vbox {\poemframed {\startpoemlines \getpoem \stoppoemlines}} \edef\poemhsize{\the\dimexpr(\hsize-\wd\scratchbox)/2\relax} \setupnarrower[poemnarrower][left=\poemhsize] \startpoemlines \getpoem \stoppoemlines \stopsetups % questo codice rientra ogni secondo e terzo verso \unprotect \installindentingmethod {three} {\c_spac_indentation_toggle_state\plusthree} \unexpanded\def\spac_indentation_tri_toggle_indeed {\glet\checkindentation\spac_indentation_tri_toggle} \unexpanded\def\spac_indentation_tri_toggle {\gdef\checkindentation {\spac_indentation_remove \gdef\checkindentation{\spac_indentation_tri_toggle_indeed}}} % this next macro is redefinition of a core macro! \def\spac_indentation_check_toggle {\ifcase\c_spac_indentation_toggle_state % nothing \or \spac_indentation_no_toggle \or \spac_indentation_do_toggle \or \spac_indentation_tri_toggle \fi} \protect % questo codice attiva il rientro \setupindenting[yes,1em] \setuplines[indenting=three] \starttext \startpoem Per correr miglior acque alza le vele omai la navicella del mio ingegno, che lascia dietro a sé mar sì crudele; e canterò di quel secondo regno dove l'umano spirito si purga e di salire al ciel diventa degno. Ma qui la morta poesì resurga, o sante Muse, poi che vostro sono; e qui Calïopè alquanto surga, seguitando il mio canto con quel suono di cui le Piche misere sentiro lo colpo tal, che disperar perdono. \stoppoem \stoptext Il giorno gio 2 lug 2020 alle ore 17:14 Tommaso Gordini < illinguista1972@gmail.com> ha scritto:
Thanks, Wolfgang. Your example works, but the verse indentation ( \setuplines[indenting=three]) is lost. There's a way to preserve it?
Tommy