Just in time for Remembrance Day (Veterans Day in the U.S.), the USPTO has added a series of cross-reference art collection subclasses (901-939) to Class 89, Ordnance. The changes are outlined in Classification Order #1889, which was published on October 6. Class 89 was created in 1901 and includes "all guns adapted to be mounted or supported otherwise than by hand, all explosion-operated guns including hand and shoulder firearms, bomb dropping devices," and all types of artillery mounts, carriages and vehicles. The new subclasses pertain to armor.
Curiously, Class 89 also includes a subclass for "methods of waging war." Some patents included in this eclectic subclass include a "friendly fire prevention system and methods" (US 6,986,302), a "method of protecting a space vehicle" from a laser weapon (US 5,323,682) and a 1943 patent (US 2,313,388) for a "vehicle impeding device," a sort of anti-tank device that looks like a caltrop, an iron three or four pointed spike that was strewn on a battlefield to stop cavalry.
According to the USPTO database, 20,585 patents and 1,066 published applications are classified in Class 89.