Where there is no well-understood or agreed-on procedure for making a decision, it is said to be:

Choosing "unstructured" to describe a situation where there is no well-understood or agreed-upon procedure for making a decision is appropriate because it captures the essence of the decision-making process in that context. Unstructured decisions are typically characterized by their complexity and ambiguity, where criteria and methods to evaluate options are not clearly defined or established.

In contrast, documented decisions imply that there is existing guidance or procedures which might not be the case in unstructured environments. Semi-structured decisions lie somewhere in between; they may have some defined procedures but still include elements that require judgment and discretion. Undocumented suggests a lack of existing written procedures but does not inherently convey the absence of structure. Therefore, describing a decision-making scenario without clear guidelines or procedures as unstructured accurately reflects the nature of the decision-making challenge involved.