Copyright © 2013 by Thomas E. Dickey
XTerm's default encoding is ISO-8859-1. Here is an example:
Those characters can be translated to UTF-8.
If no translation is done, you might see something like this:
On the other hand, there is no good reason for this (VTE):
ISO-8859-1 was supported starting with the VT320.
The VT220 provided National Character Replacement
The VT320 did extend this slightly.
In these screenshots, the replacement characters are shown
Incidentally, not all of the VT220's characters have Unicode equivalents.
XTerm shows the ones that are in Unicode.