Slightly more complicated than copying or exchanging planes is adding what is in one plane to another, or extracting a portion of one plane and placing it in another. Symmetric boolean functions, such as , AND , or XOR between planes will do the work required; since the result always replaces one of the arguments, only the second plane has to be specified in each case.
The result is three more functions in addition to apzoc, namely orple, anple, and xorple, all of which have the same style of argument. Thus orple("aacd") would move all the live bits in plane 0 over to plane 1 while preserving the live bits that plane 1 already had; the other planes are preserved by self ing, including plane 0 itself.
If the copying were repented before either plane was modified further, xorple("zazz") would erase all the bits which were moved over, including those which were already there; of course, one cannot invert an completely. This time z's are needed to preserve the remaining planes.