Franks and Rubber stamps
I have used the word frank to cover all applications of a rubber stamp to a piece of paper regardless of whether a stamp was in the way.
As much research and development went into the design of the cancellation franks and inks as went into the original Penny Black stamps. After all they didn't want the stamps available for reuse.
The first frank was use before the creation of Discworld stamps and was used on the Twinning cover envelope although it was not used to cancel a stamp.
No attempt has been made to include the first date of use of any franks because their use has been lost in time. I realise that some like the Hogswatch franks could easily be dated. For most franks I have considered the colour of the frank irrelevant. However, for a few the colour did have significance.