The iterative DO sequence creates a loop that executes if a numeric value stays within a given range of values. The values can be variables derived from CLIST processing. The iterative DO sequence has the following structure:

DO variable = from_expression TO to_expression + 
[BY by_expression]
⋮
  (action)
⋮
END

where:

variable

is the control variable for the loop. Its value changes each time the loop executes, increasing by one (the default) or by a value that you specify in the BY expression.

from_expression

is a decimal integer, or an expression that evaluates to a decimal integer, from which the control variable starts. The CLIST sets the control variable to this value when the loop begins.

to_expression

is a decimal integer, or an expression that evaluates to a decimal integer, that the control variable must increase or decrease to. The CLIST executes the loop if the value of the control variable stays within the range created by the FROM and TO expressions.

by_expression

is a decimal integer, or an expression that evaluates to a decimal integer, by which the control variable increases or decreases. The default value is one. After the loop executes, the control variable increases or decreases by this amount. If the control variable is no longer within the FROM-TO range, execution continues at the instruction after the END statement.

For example, a CLIST need to execute the following loop ten times:

DO &count = 1 to 10       /* using default BY, increase &count by one
                          /* each time through the loop
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END                       /* &count is now equal to 11

And a CLIST need to execute the following loop five times:

DO &count = 1 TO 10 BY 2  /* increase &count by two
                          /* each time through the loop
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END                       /* &count is now equal to 12

The FROM, TO, and BY expressions can all contain CLIST variables:

DO &count = &min TO &max BY &increment
⋮
END