20. canonical forms
Meromorphic 1-form systems and the canonical divisor: removable singularities, differentials of canonical forms, and existence of a nonconstant meromorphic function / nonzero ω₀ (via cohomological χ).
6 modules, 2,451 lines, under Jacobians/CanonicalForms/.
References: Forster §17.4 · Forster §16 · Forster §17 · Forster GTM 81, §17.4.