2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/147996Within the standard electroweak model we point out that the $3\times 3$ matrix of quark mixing is characterized by three universal (rephasing-invariant) quantities: one of them for $CP$ violation and the other two for off-diagonal asymmetries. Unitarity of the quark mixing matrix can in principle be tested through a variety of measurements which are irrelevant to the existence of $CP$-violating effects.Two new paragraphs, together with three relevant references, are added. We find an interesting hierarchical relation among the nine elements of the CKM matrix; and estimate the nine different angles of the six unitarity trianglesHigh Energy Physics - Phenomenologytext