Just a short memo.
We have seem that the sBoostrap, which is really a way to produce Chan-Paton labels, drives naturally to SU(15) and then perhaps to SO(30). Which was very encouraging because we know an open string needs to have a SO(32) group asociated to it. Sometimes this group is justifyed as 2^5, with 5 being half of the dimension of space, and it is related to a SO(8192) for bosonic strings.
Our justification to choose the charges, on the other hand, is that they correspond to light quarks. This should be, that there is some way to give mass to the particles in a SO(32) and only the light quarks survive, available to be used as Chan-Paton labels, and then it is Chan-Paton all the way down.
But the real justification for SO(32) is to have an anomaly-free theory. So the question is if our recursivity could be related to anomaly-matching conditions in the way of ‘t Hooft.
There is still the question of why or how some particles get mass, some others travel free. We have not problems with the leptons, they could also be massless but unable to bind into the string due to the lack of colour. Even some coloured objects could we unable to bind if they have not both chiralities available. Well, the point here is that if we consider light quarks plus leptons we are into 84 degrees of freedom and then again in the world of 11D sugra representations.