Hello,
The Processing reference calls this form:
A second type of for structure.
https://docs.oracle.com/javase/tutorial/java/nutsandbolts/for.html states:
This form is sometimes referred to as the enhanced for statement, and can be used to make your loops more compact and easy to read.
:)
Update:
There is more discussion about the enhanced for loop in the Processing references here:
Arrays / Processing.org A paragraph near bottom.
Array / Reference / Processing.org A comment in code.