The if structure tests for a condition and, if the condition is true, executes one or more command statements that follow.

Optionally, an if structure may be followed by an else structure containing one or more command statements that will execute if the condition of the if structure is false.

There are multiple forms of this structure, some that are compact and allow a single statement and others that support multiple statements.

The repeat for structure executes one or more command statements for exactly the number of specified times. The number specified can be any source that yields a positive integer.

The repeat forever structure continuously executes one or more command statements, until an exit statement is encountered.

The repeat until structure continuously executes one or more command statements, until the specified condition becomes true. The condition is checked prior to the first and any subsequent executions of the loop.

The repeat while structure continuously executes one or more command statements, while the specified condition is true. The condition is checked prior to the first and any subsequent executions of the loop.

The repeat with structure executes one or more command statements until the number in the specified variable either increases or decreases to the finish value.

Prior to the first execution of the loop, the variable is assigned the start value and with each subsequent execution of the loop, the variable is either incremented or decremented by 1.