half-width characters, so occupying one space); another common example is '%' (the percent sign), which has the five kana reading pāsento. Mixed readings There are many kanji compounds that use a mixture of on'yomi and kun'yomi, known as or words (depending on the order), which are themselves examples of this kind of compound (they are autological words): the first character of jūbako is read using on'yomi, the second kun'yomi (on-kun, 重箱読み). It is the other way around with yu-tō (kun-on, 湯桶読み). Formally, these are referred to as and . Note that in both these words, the on'yomi has a long vowel; long vowels in Japanese generally are derived from sound changes common to loans from Chinese, hence distinctive of on'yomi. These are the Japanese form of hybrid words. Other examples include , and . Ateji often use mixed readings. For instance the city of Sapporo (サッポロ), whose name derives from the Ainu language and has no meaning in Japanese, is written with the on-kun compound (which includes sokuon as if it were a purely on compound). Special readings Gikun () and jukujikun () are readings of kanji combinations that have no direct correspondence to the characters' individual on'yomi or kun'yomi. From the point of view of the character, rather than the word, this is known as a (nankun, "difficult reading"), and these are listed in kanji dictionaries under the entry for the character. Gikun are other readings assigned to a character instead of its standard readings. An example is reading (meaning "cold") as fuyu ("winter") rather than the standard readings samu or kan, and instead of the usual spelling for fuyu of . Another example is using (lit. "smoke grass") with the reading tabako ("tobacco") rather than the otherwise-expected readings of kemuri-gusa or ensō. Some of these, such as for tabako, have become lexicalized, but in many cases this kind of use is typically non-standard and employed in specific contexts by individual writers. Aided with furigana, gikun could be used to convey complex literary or poetic effect (especially if the readings contradict the kanji), or clarification if the referent may not be obvious. Jukujikun are when the standard kanji for a word are related to the meaning, but not the sound. The word is pronounced as a whole, not corresponding to sounds of individual kanji. For example, ("this morning") is jukujikun. This word is not read as *ima'asa, the expected