[Groff] Scope of .char, .fchar, .schar?

[Dorai Sitaram]

I had the following 
.char ∖ \[u005C]
in a file (the first ∖ is U+2216, or set-minus) and used set-minus within the 
same file, and it works fine.
However, when I place the .char call in a different file, and source it via .so 
or .mso, occurrences of set-minus in the sourcing file don't translate.
This happenis only when the first argument of .char is non-ascii Unicode. 
Is this expected behavior?
Thanks,--d