A commonly seen example is the double happiness symbol 囍, formed as a ligature of 喜喜 and referred to by its disyllabic name (simplified Chinese: 双喜; traditional Chinese: 雙喜; pinyin: shuāngxǐ). In handwriting, numbers are very frequently squeezed into one space or combined – common ligatures include 廿 niàn, "twenty", normally read as 二十 èrshí, 卅 sà, "thirty", normally read as 三十 sānshí, and 卌 xì "forty", normally read as 四十 "sìshí". In some cases counters are also merged into one character, such as 七十人 qīshí rén "seventy people". Another common abbreviation is 门 with a "T" written inside it, for 問題, 问题, wèntí ("question; problem"), where the "T" is from pinyin for the second syllable tí 题. Since polysyllabic characters are often non-standard, they are often excluded incharcter dictionaries.

What characters are often non-standard?