these acceleration models. When $\boldsymbol{\mu} \cdot \boldsymbol{\Omega} > 0$, where $\boldsymbol{\mu}$ is the magnetic moment, the direction of the current in the PC and SG is inward, and while the current in the OG is outward. When $\boldsymbol{\mu} \cdot \boldsymbol{\Omega} < 0$, the directions are reversed. Looking at various pulse shapes from radio to gamma-rays, people sometimes speculate all these types of acceleration co-exist. If all of these acceleration models exist above the same last open field line, the directions of the currents in these models are opposite. Therefore, it seems to be impossible that polar-slot gap and OG exist above the same last open field lines consistently from the theoretical prospective.

On the other hand, most of the observed radio and gamma-ray features of both normal and millisecond pulsars are well reproduced by radio emission from upper part of the PC region and gamma-ray emission from the SG or OG (eg, [@b13; @b8]). It is required on the observational side that the PC and SG and/or OG co-exist.

To understand the formation mechanism of the PC, SG and OG in view of electrodynamics, particle simulation for the global magnetosphere would be a powerful way. By using GRAPE [@b14], a 