T{?:x:xxxI:y:f:z:}
T{?:x:=I:y:f:z:}
T{T{?:x:xxxI:y:f:z:}:a:T{?:x:=I:y:f:z:}:b:}
{'names':['x','y','z'], 'formats':['?','<u4','<f4'], 'offsets':[0,4,8], 'itemsize':12}
[('x', '?'), ('y', '<u4'), ('z', '<f4')]
[('a', {'names':['x','y','z'], 'formats':['?','<u4','<f4'], 'offsets':[0,4,8], 'itemsize':12}), ('b', [('x', '?'), ('y', '<u4'), ('z', '<f4')])]
s:0,0,0
s:1,1,1.5
s:0,2,3
p:0,0,0
p:1,1,1.5
p:0,2,3
n:a=s:0,0,0;b=p:1,1,1.5
n:a=s:1,1,1.5;b=p:0,2,3
n:a=s:0,2,3;b=p:1,3,4.5