BEIJING — “Ma,” a Chinese character for horse, is the 13th most common family name in China, shared by nearly 17 million people. That can cause no end of confusion when Mas get together, especially if those Mas also share the same given name, as many Chinese do.

Ma Cheng’s book-loving grandfather came up with an elegant solution to this common problem. Twenty-six years ago, when his granddaughter was born, he combed through his library of Chinese dictionaries and lighted upon a character pronounced “cheng.” Cheng, which means galloping steeds, looks just like the character for horse, except that it is condensed and written three times in a row.

The character is so rare that once people see it, Miss Ma said, they tend to remember both her and her name. That is one reason she likes it so much.

That is also why the government wants her to change it.

For Ma Cheng and millions of others, Chinese parents’ desire to give their children a spark of individuality is colliding head-on with the Chinese bureaucracy’s desire for order. Seeking to modernize its vast database on China’s 1.3 billion citizens, the government’s Public Security Bureau has been replacing the handwritten identity card that every Chinese must carry with a computer-readable one, complete with color photos and embedded microchips. The new cards are harder to forge and can be scanned at places like airports where security is a priority.