  We construct representations of the Heisenberg algebra by pushing the
perturbation expansion to high orders. If the multiplication operators
$B_{1,2}$ tend to differential operators of order $l_{2,1}$, respectively, the
singularity is characterized by $(l _{1},l_{2})$. Let $l_{1} \geq l_{2}$. Then
the two cases A : ``$l_{2}$ does not divide $l_{1}$'' and B : ``$l_{2}$ divides
$l_{1}$'' need a different treatment. The universality classes are labelled
$[p,q]$ where $[p,q]$=[$l_{1}$,$l_{2}$] in case A and
$[p,q]$=[$l_{1}+1$,$l_{2}$] in case B.
