I know that the answer to the question "What occurred in the 19th year of the 20th century?" is in "In 1901, 10-inch disc records were introduced, followed in 1903 by 12-inch records. These could play for more than three and four minutes respectively, while contemporary cylinders could only play for about two minutes. In an attempt to head off the disc advantage, Edison introduced the Amberol cylinder in 1909, with a maximum playing time of 4½ minutes (at 160 rpm), which in turn were superseded by Blue Amberol Records, which had a playing surface made of celluloid, a plastic, which was far less fragile. Despite these improvements, during the 1910s discs decisively won this early format war, although Edison continued to produce new Blue Amberol cylinders for an ever-dwindling customer base until late in 1929. By 1919 the basic patents for the manufacture of lateral-cut disc records had expired, opening the field for countless companies to produce them. Analog disc records would dominate the home entertainment market until they were outsold by the digital compact disc in the late 1980s (which was in turn supplanted by digital audio recordings distributed via online music stores and Internet file sharing).". Can you tell me what it is?
Answer:
the basic patents for the manufacture of lateral-cut disc records had expired, opening the field for countless companies to produce them