Update: 2 additional identifiers that allow creating &binvar names containing a space.
1d. $fread
//fopen foo mirc.ini | echo -a $fread(foo,10,&foo bar) | echo -a $bvar(&foo) vs $bvar(&foo bar) | fclose foo
1e. $cb
//clipboard test | echo -a $cb(-1,,&foo bar) : $bvar(&foo) vs $bvar(&foo bar)