

This post has been corrected. See the note at the bottom for details.

BEIJING -- The stock market played a strange trick on the Chinese Communist Party on Monday.

Whether a cosmic joke or coincidence -- or as some wags suggested, an act of God -- the Shanghai stock market index fell 64.89 points on Monday, which happened to be June 4, the 23rd anniversary of the 1989 crackdown on pro-democracy demonstrators at Tiananmen Square.

This darkest moment in recent Chinese history is customarily referred to as 6/4, the unembellished number conveying the same stark tragedy as 9/11 for Americans.

In the numerology of censorship, nothing is more sensitive. There is a ritualized cat-and-mouse game every year on this date between the censors and those who want to commemorate the death of hundreds, perhaps thousands. On the 20th anniversary, an advertisement managed to slip into a newspaper showing two groups of people -- six on one side and four on the other -- gazing philosophically toward the sky.

Nowadays, the game is largely played out on the Internet. The number 6/4 is banned by censors –- as is 5/35, an attempt to get around the bans by referring to the date as the 35th of May. Other words that were scrubbed on Monday were “candle,” “commemorate,” “massacre,” “tank” and “never forget.”