In Traveller-5, worldgen step E includes creating the world’s cultural extension (Cx), the last digit of which is “symbols.” The rule book explains only that:
Symbols used by the culture may range from the concrete (idol; totems; statuary) to the abstract (symbolized belief systems; group affiliations).
Given that the value is computed as Tech Level + Flux with a minimum of 1, one can easily infer that more primitive cultures have a lower value while more advanced cultures have a higher value. One also might infer from the brief description that the axis it measures has more “concrete” symbols at the lower range and more “abstract” symbols at the higher end.
How is this value applied to describing the world’s culture?
[Responses relevant to other editions of Traveller besides 5 are useful.]