A type of long Chinese jacket
Chang-ao (), lit. translated as "long jacket" or "long "ao"", is a historical long-length, Chinese upper garment called "ao" (袄), which was worn by women. It is also known as da ao (大袄) and chang ru (长襦; long "ru" jacket) which appears to be the precursor of the "ao". 
When paired with a skirt, the "chang-ao" forms a style of "aoqun" (i.e. jacket worn over a skirt). This set of attire is worn as a formal attire. 
History.
In the Ming dynasty, the wearing of long-length upper jacket (ao) with skirts became more prevalent than the wearing of short upper jacket with skirts. Several paintings, book illustrations, tomb artefacts, and references from books which dates from the late Ming dynasty show that women were wearing long-length "ao" with a skirt during this period.
The combination of long-length "ao" with skirt continued to exist in the Qing dynasty. However the style of Ming dynasty "ao" continued to evolve under the influence of the Manchu fashion. By the late Qing dynasty, it was typical for the "ao" to be waist-length. The late Qing "ao" also had different types of opening (i.e. central front opening, slant opening), could have either narrow or wide sleeves and could have a mandarin collar.
After the fall of the Qing dynasty, the "ao" continued to be worn in the Republic of China; the 1910s "ao" style was once again lengthen up to hip level, and sometimes up to the knees. It was once again shortened in the 1920s to be waist-length.
Construction and design.
The "chang-ao" was actually developed from zhiduo during the Ming Dynasty, and is worn over a skirt. It is wide-sleeved, shorter than zhiduo and has no side panels (暗擺) at the side slits (thus showing the skirt worn underneath). There is often an optional detachable protective huling (護領, lit. "protect collar") sewn to the collar. The huling can be of white or any other dark colours. The collar is of the same colour as the clothing. 
References.
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