<P> Compartments also held spacers, which are blocks of blank type used to separate words and fill out a line of type, such as em and en quads (quadrats, or spaces . A quadrat is a block of type whose face is lower than the printing letters so that it does not itself print .). An em space was the width of a capital letter "M"--as wide as it was high--while an en space referred to a space half the width of its height (usually the dimensions for a capital "N"). </P> <P> Individual letters are assembled into words and lines of text with the aid of a composing stick, and the whole assembly is tightly bound together to make up a page image called a forme, where all letter faces are exactly the same height to form a flat surface of type . The forme is mounted on a printing press, a thin coating of viscous ink is applied and impressions made on paper under great pressure in the press . "Sorts" is the term given to special characters not freely available in the typical type case, such as the "@" mark . </P> <P> Sometimes it is erroneously stated that printing with metal type replaced the earlier methods . In the industrial era printing methods would be chosen to suit the purpose . For example, when printing large scale letters in posters etc. the metal type would have proved too heavy and economically unviable . Thus, large scale type was made as carved wood blocks as well as ceramics plates . Also in many cases where large scale text was required, it was simpler to hand the job to a sign painter than a printer . Images could be printed together with movable type if they were made as woodcuts or wood engravings as long as the blocks were made to the same type height . If intaglio methods, such as copper plates, were used for the images, then images and the text would have required separate print runs on different machines . </P>

What was movable type used for in china