Involved in degradation of plant cell wall polysaccharides. Has endo-xylanase activity towards substrates such as oat spelt xylan (OSX), acetylated xylo-oligosaccharides and acetylated xylan, producing primarily xylobiose; cannot hydrolyze xylobiose to xylose. Also has feruloyl esterase activity, releasing ferulic acid from methylferulate, and from the more natural substrates wheat bran, corn fiber, and XOS(FA,Ac), a corn fiber-derived substrate enriched in O-acetyl and ferulic acid esters. Exhibits negligible acetyl esterase activity on sugar acetates. Acts synergistically with Xyl3A to increase the release of xylose from xylan. Does not possess endoglucanase or mannanase activities since it is not able to hydrolyze carboxymethyl cellulose and locust bean gum. Endohydrolysis of (1->4)-beta-D-xylosidic linkages in xylans. feruloyl-polysaccharide + H2O = ferulate + polysaccharide. Optimum pH is 6.0 for xylanase activity. Glycan degradation; xylan degradation. Monomer or homodimer. By growth on ester-enriched corn oligosaccharides. The two catalytic domains appear to be functionally coupled. In the N-terminal section; belongs to the glycosyl hydrolase 10 (cellulase F) family.