The raw text is like this:<words> command feed world </words> tag=random      <words> who is that ? </words> tag=normalI need to substitute words for characters:<words> c o m m a n d  f e e d  w o r l d </words> tag=random<words> w h o  i s  t h a t ? </words> tag=normalI know how to do it if the range is over lines, but don't know how to do it if the range is in a line..My solution: %s:<words>.*\zs(.)\ze.*</words>:\1 :gcWithout any doubt it does not work. 
Substitute words for characters between matches in a line?
regular expression;substitute