Reuse the last direction if there's no direction specified in the command.

[ghost]

If the command dose not have any direction specified, then use the last used direction.

Rule110 would be:

0! 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 1 0
40

outer: 1 sub dup 2 eq outer_end jmpif
  trace

  !1 shl 7 and or
  
  0!
    loop: !over 2 < end jmpif
      1 shl 7 and or

      dup 1 swap shl
      110 swap and
      over shr
      move
    loop jmp
    end:
  0!
  
  !drop
  move
outer jmp
outer_end:

which is way cleaner.