Yǒu biān dú biān
Yǒu biān dú biān, or dú bàn biān, is a rule of thumb people use to pronounce a Chinese character when they do not know its exact pronunciation. A longer version is '，'.
Around 90% of Chinese characters are phono-semantic compounds that consist of two parts: a semantic part that suggests a general meaning, and a phonetic part which shows how the character is or was pronounced.
The phonetic part represents the exact or almost-exact pronunciation of the character when the character was first created; characters sharing the same phonetic part had identical or similar readings. Linguists rely heavily on this fact to reconstruct the sounds of [ancient Chinese]. However, over time, the reading of a character may be no longer the one indicated by the phonetic part due to sound change and general vagueness.
When one encounters such a two-part character and does not know its exact pronunciation, one may take one of the parts as the phonetic indicator. For example, reading Wiktionary:詣 as zhǐ because its "side" Wiktionary:旨 is pronounced as such. Some of this kind of "folk reading" have become acceptable over time – listed in dictionaries as alternative pronunciations, or simply become the common reading. For example, people read the character Wiktionary:町 ting in 西門町 as if it were Wiktionary:丁 ding. It has been called a "phenomenon of analogy", and is observed in as early as the Song dynasty.