Control Structures

The statements in a processing block are organized in control structures. These define statement blocks and control the progress of the program within a processing block. They determine the conditions for processing statement blocks and how often this happens. Control structures can be nested. Statement blocks in control structures can themselves contain control structures.

The following control structures exist:

• Sequence
  A sequence consists of a statement block that is not defined explicitly by control statements. The statements it contains are processed once without conditions. The execution of a sequence can be suspended for a certain time using a WAIT statement.

• Branch (selection)
  A branch comprises one or more statement blocks defined by control statements such as IF or CASE, and that are executed according to conditions.

• Loop (iteration)
  A loop comprises a statement block that is defined by control statements such as DO or WHILE, and that can be executed several times.