! Tags to be appended to an fst to get spell-relax tags:
define spellrelax [
 á (->) a "aaX" ,
 a (->) á "aaX" ,
 č (->) c "aaX" ,
 c (->) č "aaX" ,
 š (->) s "aaX" ,
 z (->) ž "aaX" ,
 ž (->) z "aaX" || _ ?* "^a2aa" ];

define Restr1 "^a2aa" => "aaX" ?* _ ;

define Clean "aaX" -> 0,
           "^a2aa" -> 0;

read regex spellrelax .o.
           Restr1     .o.
           Clean ;