ruby characters

Originally typesetters’ lingo for interlinear citations for a letter with a five-and-a-half point (about a pica) height—the US using a standard called agate which is also in newsprint the smallest legible text, the title refers to mark-up notations or glosses that appear above or to the side of logographic glyphs to aid in or clarify pronunciation—and sometimes as a means to communicate puns or entendre. In Japanese, the phonetic courtesy characters are called furigana and in Mandarin, Bopomofo—from the first four letters of the system: ㄅ, ㄆ, ㄇ and ㄈ. 東京 ( とうきょう)
東京 ( Tōkyō)