2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/40381An attempt is made to sort out ambiguities existing in the current usage of several basic concepts describing hard collisions of photons. It is argued that appropriate terminology is often a prerequisite for correct physics.9 pages, EPJC macro, 10 figures in eps format slighly shortened version, two figures removed, references updatedHigh Energy Physics - Phenomenologytext