Definitions for "Predates"
stamps or postal stationery postmarked with dates prior to the official first day of issue. These are not First Day Covers, EDU s or EKU
Predates are stamps or postal stationery postmarked with dates earlier than the officially designated First Day of sale. In general, predates are not valued higher than First Day Covers other than for novelty, and they are not considered as earliest known usage, EDUs or EKUs.