 Formal monodromy

An unramified formal fundamental matrix $\hat{Y}=\hat{G}(\lambda ){\lambda }^{\Theta }{e}^{Q(\lambda )}$ acquires the right factor $e^{2\pi i\Theta }$ on a positive turn of the logarithm branch. This is formal monodromy. It can be nontrivial even when the true equation has an entire fundamental matrix and trivial actual monodromy, because Stokes matrices compensate for it.