1. A method comprising: maintaining, on computer-readable media, a hierarchical representation of a plurality of nodes associated with a corresponding plurality of objects in a virtual space, the hierarchical representation indicating relationships between respective nodes, wherein at least some of the plurality of objects are associated with respective executable scripts, and wherein a first node having a higher position in the hierarchical representation than a second node in the hierarchical representation is associated with a first executable script; determining a modification permission for the first executable script, the modification permission associated with a second object associated with the second node in the hierarchical representation, the determination based on at least the hierarchical relationship between the first node and the second node, wherein the modification permission indicates whether the first executable script is permitted to modify the second object; and executing the first executable script on one or more computer processors in communication with the computer-readable media in accordance with the determined modification permission.