A description of a book's current and original structure, that is, the arrangement of its leaves and quires. This information may be conveyed in diagrammatic form (showing the quires and their composition) or in a prose shorthand. In the latter, for example, '18 (wants 1, blank)' indicates that the first quire was formed of eight leaves, the first of which is missing and was probably originally blank. Two collations may be given to indicate differences between a book's current and original structures, but a single collation can often convey data relevant to both states. (This type of physical collation is not to be confused with textual collation or comparison.).