The main parts of the LHC diffractive physics programme possible to be
measured using a proton tagging technique are presented. The geometric
acceptance of the ATLAS forward proton detectors: ALFA and AFP for various LHC
optics settings are shown. The probabilities of observing a proton originating
from a minimum-bias event in ALFA and AFP stations are given. The main
properties of single diffractive and double Pomeron exchange production of
dijets, photon+jet, jet-gap-jet and W/Z bosons are discussed. The possibility
of measuring the jet production in exclusive (double proton tag) and
semi-exclusive (single tag) mode is evaluated