xclock -strftime option misinterprets/mishandles the %n specification
When xclock is invoked with both the -digital and -strftime options, the man page for xclock(1) suggests that the string given as the argument to the -strftime option will be interpreted as if it were a format specification given to the strftime() libc function.
This is mostly true with the exception of the %n (newline) conversion specification, which is seriously mishandled by xclock. Instead of introducing a newline at that point in the rendered digital clock image, xclock instead displays something that looks like an empty box character at the corresponding point in the rendered digital clock image.
This is just wrong, and it obviously violates the Principal of Least Surprise. If the user has explicitly requested a newline at some certain point in the format string, then he/she did so for a reason, and xclock should honor that request by splitting the rendered digital xclock image across two (or more) lines, exactly as the user had explicitly requested. There is no compelling reason not to do so.
P.S. This issue was originally reported only for FreeBSD 12.0-RELEASE. I was asked to report it here also, as it is fundamentally a cross-platform issue with xclock.