As there are no file name restrictions for ASCII characters, I assume this requirement might be outdated. Is that correct?
Index: intro.2 =================================================================== RCS file: /cvs/src/lib/libc/sys/intro.2,v retrieving revision 1.53 diff -u -p -r1.53 intro.2 --- intro.2 10 Dec 2014 07:18:44 -0000 1.53 +++ intro.2 15 Dec 2014 11:11:06 -0000 @@ -595,12 +595,8 @@ Names consisting of up to 255 characters may be used to name an ordinary file, special file, or directory. .Pp -These characters may be selected from the set of all -.Tn ASCII -character -excluding 0 (NUL) and the -.Tn ASCII -code for +These characters may be arbitrary eight-bit values, +excluding 0 (NUL) and the ASCII code for .Ql \&/ (slash). .Pp @@ -615,7 +611,7 @@ file names because of the special meanin by the shell. .Pp Note also that -.Pq Dv NAME_MAX +.Dv NAME_MAX is an upper limit fixed by the kernel, meant to be used for sizing buffers. Some filesystems may have additional restrictions. These can be queried using @@ -623,8 +619,7 @@ These can be queried using and .Xr fpathconf 2 . .It Path Name -A path name is a -.Tn NUL Ns -terminated +A path name is a NUL-terminated character string starting with an optional slash .Ql \&/ ,
