- indicia: Indicia (philately) - Wikipedia
- franking: Franking - Wikipedia
- imprinted stamp: Imprinted stamp - Wikipedia
Especially for the first 2 ones, both of them seems to be referred to something like “a marking that represents postage”. The reason for put the 3rd one here is that “other permit Imprints (Indicia)” in was mentioned in “Franking Wikipedia page”.
Anyone who knows the differences? Sincerely thanks in advance.