Hallo,

zu den "Date stamp cards" von Südafrika + Homelands habe ich folgende Info im Internet gefunden:

Introduction

Pictorial cancels, usually for Philatelic events and/or other specific occasions are usually applied to plain unaddressed postcards known as ‘Date Stamp Cards’. Initially such cards enjoyed a specific design for the occasion but soon gave way to a ‘Standard’ design which was changed over time.

Gruß
limingerald