Xylan 1,4-beta-xylosidase involved in the hydrolysis of xylan, a major structural heterogeneous polysaccharide found in plant biomass representing the second most abundant polysaccharide in the biosphere, after cellulose. Active against rye arabinoxylan and xylohexaose, but not paranitrophenyl-beta-xyloside. Hydrolysis of (1->4)-beta-D-xylans, to remove successive D-xylose residues from the non-reducing termini. Optimum pH is 4.4. Optimum temperature is 48 degrees Celsius. Glycan degradation; xylan degradation. Belongs to the glycosyl hydrolase 3 family.