Modifying a ruling when customs change

Dr. Mustafa al-Khin writes:

“Certain customs are permanent; that is, they do not change with time or location. Accordingly, the ruling of these customs is established and is not subject to modification or change. Other customs change and evolve due to location or time. In such circumstances, it is obligatory for a ruling to be modified in accordance with custom. This is based on the principle “The modification of a ruling because of changing customs cannot be censored.” An example of this is the lira. Originally, the term lira was used exclusively for gold lire, but in the present era, the usage of lira extends to modern paper money. Consequently, whenever a transaction takes place, and the buyer or seller uses the term lira, it must be understood in accordance with the custom of that locality (al-Kafi al-Wafi pg. 216).”