Today because carpets are produced in 23 provinces, municipalities, and autonomous regions of mainland China, maintenance of quality standards has become very important. Ansari discusses definitions and specifications for different qualities of knotting (90 knots per linear foot is the most common standard for wool carpets; 120 for silk) and wools as well as for special carpets like Peking Antique Finished Carpets (reproductions dyed with vegetable, rather than chrome, dyes). -- AATA