The basic stamps of these issues were printed on various types of papers, depending on what was available at the printing press in Chungking. Paper types listed are:

Native Paper with Lines (horizontal, diagonal, and vertical)

Thin Native Paper without Lines

Thick Native Paper without Lines

Chinese Wood Free Paper

Foreign Wood Free Paper

Thick Revenue Type Paper (very scarce)

There are three tyu[pes of the overprint "Restricted For Use in Sinkiang" on the stamps of the Central Trust SYS. 

Type 1: The left hand character is taller and narrower and the left vertical stroke bends outward more than the other two types. In the center character the right side of the lower section is slanted inwards and the top long dots do not touch other parts of the character. In the second from the left character the legs do not touch the line above. 

Type 2: These were sold only in Chungking, the wartime capital in eastern Szechwan province. The left hand character is more nearly square and the left vertical stroke bends outward less than in Type 1. In the center character the bottom part is wider and the sides are straighter than Type 1 and the long dots at the top are equally distant from the top of the vertical stroke. 

Type 3: These overprints can be distinguished by thinner strokes throughout, particularly noticeable in the second character from the left, which is tall and thin with thin and balanced legs. In the center character the left long dot touches the diagonal stroke.