2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/55829We begin a classification of the symmetry algebras arising on configurations of type IIB [p,q] 7-branes. These include not just the Kodaira symmetries that occur when branes coalesce into a singularity, but also algebras associated to other physically interesting brane configurations that cannot be collapsed. We demonstrate how the monodromy around the 7-branes essentially determines the algebra, and thus 7-brane gauge symmetries are classified by conjugacy classes of the modular group SL(2,Z). Through a classic map between the modular group and binary quadratic forms, the monodromy fixes the asymptotic charge form which determines the representations of the various (p,q) dyons in probe D3-brane theories. This quadratic form also controls the change in the algebra during transitions between different brane configurations. We give a unified description of the brane configurations extending the D_N, E_N and Argyres-Douglas H_N series beyond the Kodaira cases. We anticipate the appearance of affine and indefinite infinite-dimensional algebras, which we explore in a sequel paper.32 pages LaTeX, 4 eps figures. A relation between the trace of the monodromy and the determinant of the Cartan matrix is established. The role of the asymptotic charge constraint is clarifiedHigh Energy Physics - Theorytext