A product taxonomy that has no limits or rules governing the number of levels, the quantity and size of nodes, or the labeling of categories.
Unconstrained Hierarchy is often a more theoretical construction of what a given taxonomy would look like in a perfect world. Most hierarchies, especially product hierarchies, must have some constraints. These constraints could be due to deadlines, expense, or the limits of the hosting software. However, understanding how an Unconstrained Hierarchy would look for a set of products is helpful information for working around structuring and labeling compromises and for building out schema that help to differentiate the products.