WinBUGS uses “precision” as a parameter in specifying a Normal distribution, instead of variance.

Precision = $\frac{1}{\text{Variance}}$

`dnorm(0, 0.0001)` is the same as a Normal distribution with mean
0 and variance $\frac{1}{0.0001} = 100^2$, or $\sim \mathcal{N}(0,1)$