me_frame particle numbering scheme

Dear madgraph Experts,

I have a question concerning the Madgraph tool for automation of polarized matrix element computations, described in this publication: https://arxiv.org/pdf/1912.01725.pdf
A new option called "me_frame" is introduced to define the polarisation reference frame and a particle numbering scheme, numbering the initial and final state particles, has to be used in this option. I wonder how the counting/numbering is defined.

Let's define the process

generate p p > w z j j QCD=0, w+ > l+ vl, w- > l- vl~, z > l+ l- @0

This describes the electroweak production of W and Z bosons in association with 2 jets, the bosons decay leptonically. l are leptons (electron or muons), vl is the corresponding lepton neutrino, "w" can be the positively or negatively charged W boson.

Does the counting in the syntax of "me_frame" refer to the final state particles "w z j j" or to the final state leptons (l vl l l j j )?

As an example, if I want to define the WZ restframe, do I have to define
me_frame = "3,4,5,6" (referring to final state leptons: l vl l l j j)
OR
me_frame = "3,4" (referring to the particles as in "w z j j")

Thanks!