Dear Wolfgang, I found the following code with a comment “code by Wolfgang” at https://adityam.github.io/context-blog/post/metapost-animation/ https://adityam.github.io/context-blog/post/metapost-animation/ \unprotect \installnamespace{MPanimationvariables} \unexpanded\def\startMPanimation {\dodoublegroupempty\meta_start_animation} \def\meta_start_animation#1% {\normalexpanded{\meta_start_animation_indeed{#1}}} \unexpanded\def\meta_start_animation_indeed#1#2#3\stopMPanimation {\doifsomething{#2}{\getparameters[\????MPanimationvariables#1:][#2]}% \setgvalue{\??mpgraphic animation:#1}{\meta_handle_use_graphic{#1}{n,t}{#3}}} \let\stopMPanimation\relax \unexpanded\def\useMPanimation% {\dosingleargument\use_meta_animation} \def\use_meta_animation[#1]#2% {\edef\c_MP_animation_frames{\getvalue{\????MPanimationvariables#2:n}}% \startanimation[#1] \dorecurse{\c_MP_animation_frames} {\expanded{\frame{\useMPgraphic{animation:#2}{n=\c_MP_animation_frames,t=\recurselevel}}}} \stopanimation} \protect In the code, there are many “????”.(\????MPanimationvariables#1, {\??mpgraphic animation:#1}) I wonder it is correct or not. Would you please check it? Best regards, Dalyoung