  A.A. Suslin proved a normality theorem for an elementary linear group, which
says that an elementary linear group of size bigger than or equal to 3 over a
commutative ring with unity is normal in the general linear group of same size.
Subsequently, V.I. Kopeiko extended this result of Suslin for a symplectic
group defined with respect to the standard skew-symmetric matrix of even size.
Here we generalise the result of Kopeiko for a symplectic group defined with
respect to any invertible skew-symmetric matrix of even size of Pfaffian one.
