Which of these terms describes fixed references that cannot be entered into?

The term that describes fixed references that cannot be entered into is landmarks. Landmarks serve as visual cues within a spatial environment, helping individuals orient themselves and navigate through it. They are often prominent features, such as buildings, natural formations, or distinctive sculptures that stand out within a landscape. Unlike paths, which represent routes of movement, or edges, which signify boundaries, landmarks are generally fixed points that provide a sense of location and stability but do not allow for physical entry or interaction.

Nodes, while important in a spatial context, usually denote key points of intersection or decision-making within a network where movement can occur, thus allowing for entry and transitions. In contrast, landmarks are meant to be observed rather than interacted with or entered, reinforcing their role as static reference points in navigation.