Invocation is the chief part: Saints as guardians who hear even silent prayers
The main Roman act toward the Saints is calling on them, in private and in public.
They are supposed to intercede for the Church at large and for each believer.
They are treated as guardians who see each person's need and hear prayers that are never spoken aloud.
Latin
VIII. Sed praecipuam partem cultus qui Sanctis exhiberi solet positam esse docuimus in eorum invocatione, per quam Sanctorum in Christo defunctorum opem & auxilium, privatim & publice implorant: supponentes eos non tantum in genere pro Ecclesia Militante, sed etiam pro singulis fidelibus intercedere; quin eos constitutos esse generis humani custodes, patronos, atque protectores, qui singulorum necessitates, non solum videre possint, verum etiam preces solo corde conceptas audire.