[Getdp] Galerkin Equations

[Sebastian]

Hi all:

I am new here, and new in GetDP. And I have problems to understand
the notation used in the Galerkin equations used in GetDP.

I think that I understand the first expression, but I don't known what to 
do with the second expression.

As I understand if I have:
Equation{
   Galerkin { [ -nu[] * Dof { d a }, {d a } ];
		In Domain; .....
   Galerkin{ [ hc[], { d a }];
		In Domain_M ,....
   Galerkin{ [-js[], { a } ];
  		In Domain_S , ...
}

GetDP solves d a = ( js - hs ) / nu, the summation of the first expressions 
= 0.
But, What to do with the second expressions, in Galerkin definition?

Why put { da } in the first and second Galerkins, and why put { a } in the 
third ?

Thanks.