I think I see what you want to explain. For some processes, however, the NMOS implant layer is different (has lower implant dose) from the NIMPLANT layer (to form N+ areas in the n-well). For the lower concentration NMOS implant (in the p-substrate or p-well), the ACTIVE area ANDed with the p-substrate/p-well is used. Due to the slight under-diffusion (diffusion following the implant), the NMOS implant sufficiently surrounds the NMOS ACTIVE area. By this double utilization of the ACTIVE area layer, no further NMOS implant layer is necessary.