Final answer:
Layers are the typical subsections taken when cutting a square one length above the shoulders haircut, which aims to create an even, horizontal shape around the head.
Step-by-step explanation:
When cutting a square one length above the shoulders haircut, the type of subsections that are typically taken are Layers.
This cutting technique involves creating a shape that is horizontal and even around the head at a level that falls above the shoulders. Bangs may be incorporated depending on the desired style but are not a subsection in a traditional one length cut.
An undercut is a technique used to reduce bulk or add an edge to a hairstyle by closely cutting the hair underneath longer hair, which is not inherent to a one-length square cut. In the classic form, subsections would be used to divide the hair for controlled cutting, but layers are not used to maintain a uniform length around the head.