Thank you very much for all your answers, @choroba had the correct point: tr takes only literals for both character sets. Yes there are ways around that by using the `evil' eval, but that is just not necessary in my case: I just want to write a little function that accepts an ASCII string and returns a "bold" version of it. And yes, my terminal (MobaXterm) is capable to display a pretty good chunk of the UniCode charset, including the pseudo-bold or -italic block. Again, thank you all for guiding me back to the path of truth! 😋 Best regards from Charleston (WV), Perlian