(The same is done if an existing logical name was defined in
executive or kernel mode; an existing user or supervisor mode
logical name is reset to the new value.) If the value is an empty
-string, the logical name's translation is defined as a single NUL
-(ASCII 00) character, since a logical name cannot translate to a
+string, the logical name's translation is defined as a single C<NUL>
+(ASCII C<\0>) character, since a logical name cannot translate to a
zero-length string. (This restriction does not apply to CLI symbols
or CRTL C<environ> values; they are set to the empty string.)
An element of the CRTL C<environ> array can be set only if your