have been assigned invented Sino-Japanese readings. For example, the common character has been given the reading dō (taken from ), and even been borrowed into written Chinese in the 20th century with the reading dòng. Rebus (phonetic loan) characters Jiajie () are characters that are "borrowed" to write another morpheme which is pronounced the same or nearly the same. For example, the character was originally a pictogram of a wheat plant and meant *m-rˁək "wheat". As this was pronounced similar to the Old Chinese word *mə.rˁək "to come", was also used to write this verb. Eventually the more common usage, the verb "to come", became established as the default reading of the character , and a new character was devised for "wheat". (The modern pronunciations are lái and mài.) When a character is used as a rebus this way, it is called a , translatable as "phonetic loan character" or "rebus" character. (An example using symbols familiar to English-speakers would be if a beekeeper wrote "This year we bottled £124 weight of honey".) As in Egyptian hieroglyphs and Sumerian cuneiform, early Chinese characters were used as rebuses to express abstract meanings that were not easily depicted. Thus many characters stood for more than one word. In some cases the extended use would take over completely, and a new character would be created for the original meaning, usually by modifying the original character with a radical (determinative). For instance, yòu originally meant "right hand; right" but was borrowed to write the abstract word yòu "again; moreover". In modern usage, the character exclusively represents yòu "again" while , which adds the "mouth radical" to , represents yòu "right". This process of graphic disambiguation is a common source of phono-semantic compound characters. While this word jiajie dates from the Han dynasty, the related term tongjia () is first attested from the Ming dynasty. The two terms are commonly used as synonyms, but there is a linguistic distinction between jiajiezi being a phonetic loan character for a word that did not originally have a character, such as using for dōng "east", and tongjia being an interchangeable character used for an existing homophonous character, such as using for . (But the character for "east" has also been explained as a drawing of the sun rising behind a distant tree.) According to Bernhard Karlgren, "One of the most dangerous stumbling-blocks in the interpretation of pre-Han texts