Insert:

Finally we insert the matrix in the -picture logically by ensuring that it has the right size

( @@insert@insert@@

@@insert@#1#2#3#4#5#6@MATRIX INSERT=-#1=#2#3 =-#4#5=#6 = )

: Should handle other forms than reference point at center of |"1,1"| as hardcoded here. In particular reference point at baseline of |"1,1"| would be useful...

3