@guy038 Thank you very much for your post. Symbola and Symbola_monospacified_for_LiberationMono are a reasonably comprehensive font of the Unicode character set that does what I asked for: the text files display and print as expected or planned with the new mathematical symbols with which I am experimenting. My only complaint is that it is a serif font … mutter mutter … I do like fonts like Helvetica.
Æþelleo-Durkin