Application statements comprise all X-PLOR statements that generate, manipulate, and operate on the X-PLOR data structures. There are two types of application statements: simple application statements and structured application statements. In a simple application statement, the order of assignments is strict and has to be followed exactly as specified in the syntax. Examples of simple application statements are the vector statements and the evaluate statements. In the case of a structured application statement, the statement has to be terminated by an END keyword. The order in which assignments and statements are specified is not strict, although there may be special requirements for certain structured application statements. A structured application statement may also contain control statements. Examples are the dynamics Verlet statement, which executes molecular dynamics, and the xrefin statement, which sets up the data structures for crystallographic refinement. In this book it is always understood that structured application statements may contain control statements, and explicit reference to control statements is omitted from the syntactic definitions. A list of all application statements is given at the end of the book.