Endo-1,4-beta-xylanase 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. Accounts for approximately 70 percent of the endoxylanase activity in the culture filtrate. Endohydrolysis of (1->4)-beta-D-xylosidic linkages in xylans. Glycan degradation; xylan degradation. Expressed in presence of rice cell walls or on oat spelt xylan, but not when grown on sucrose. Retains 39 percent of the catalytic activity. Double xyl1/xyl2 deletion mutant retains 19 percent of the activity and exhibits a 50 percent reduction in accumulation of total mycelial mass. Belongs to the glycosyl hydrolase 10 (cellulase F) family.