From the linguistic side there have been some misgivings about applying the term ‘symbol’ to entities that stand in a purely arbitrary relation to their interpretation. From this point of view, ‘symbol’ shoul be used only of entities that are isomorphic with their interpretation [...]. But in logistics it is customary to use the word ‘symbol’ in a far broader application, and it seems advantageous to be able to apply the word precisely to interpretable non-semiotic entities.
- Hjelmslev (1961), Pag. 113-114