The reference is the number that identifies the postcard in its series. It is generally the reference indicated by the publisher or the printer himself but it can come from a reference coming from a cartophilic inventory making reference. In this case it is good to note the origin of the reference or numbering in the card of the postcard series

Do not put anything if no reference is indicated on the card (whether on the front or back)
Do not put the publisher's abbreviations in the reference

Example: For D.V.D 8521 just indicate 8521 in the reference.

Do not confuse this field with the sort key which is by default a copy of the reference which takes into account the maximum reference of the series. For example, the sorting key of the 7th card in a series of more than 100 cards will be generated by the system and will be worth 007. This makes it possible to obtain a correct sorting of the series WITHOUT modifying the references

The postcard in a broad sense is the heart of this site. It includes all sizes of card stock intended to be sent in the open including photo-cards identified or not

The photo card has the "photo-card" printing mode. If the photo map is identified we can specify the locality, otherwise there are generic localities for each country or province of Belgium.

Different postcards will be created if the snapshots are different for the same map of a series or if the reference number is the editor or if the title is completely different. The variety of colors or presentations or title place will only be specified if this presents crucial information for relatively rare cards.

If there is a coherent set of cards from the same publisher or printer, the card will be associated with a series and possibly a set of postcards. A card set is a subset of a series of cards. See the associated documentation.