undef, undef: match
>0<, undef: different
>0<, >0<: match
><, undef: different
><, ><: match
>1<, undef: different
>1<, >1<: match
>0<, >0<: match
>0<, >0<: match
>0<, >0<: match
>0e0<, >0<: different
>x<, >0<: different
>x<, >0<: different