When Ding Mao played in Xu Jiari's seventh game, who knew what it meant?

This sentence looks like the lunar time record in ancient China, describing a certain point in time. "Xu Jiari" refers to a certain day in the year of Xu Jiari, "Ding" refers to Ding, and "seven games to apply" may refer to some geographical or astronomical phenomena, such as the location of stars, the record of geographical location, or other information related to astronomical geography. To understand the exact meaning of this sentence, more contextual information or professional knowledge may be needed.