What's the axial boundary condition?

Dear all,

I've been using 2D axisymmetric Electromagnetic module. On the axis there's the default axial boundary condition. It's very convenient to use, but there's no way to know what conditions it actually enforces behind (not only for the lowest order m = 0; also for e.g., m = 1). Now I would like to couple it with another model. It's a good attempt to specify a similar axial boundary condition in the new model. Then comes this question...

Thanks for any input!
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Pu, ZHANG
DTU Fotonik