The statements in a processing block are organized into control structures. These define statement blocks and control the program flow within a processing block. They determine the conditions under which statement blocks are processed and how often this occurs. Control structures can be nested. Statement blocks in control structures can also contain control structures.
The following control structures exist:
A sequence consists of a statement block that is not defined explicitly by control statements. The statements it contains are executed once without conditions. Program execution of a sequence can be suspended for a specific time using a
- Branch (selection)
A branch consists of one or more statement blocks defined by control statements such as
CASE, and that are executed based on conditions.
- Loop (iteration)
A loop consists of a statement block that is defined by control statements such as
WHILE, and that can be executed multiple times.
There are also special control structures for exception handling.
ON CHANGE OF is an obsolete control structure.