Express basically pulls the catalog from all the major marketplaces.
A client can select different modes of catalog pull depending on his requirements,
1) : Moderate
This particular mode simply pulls the sku's from the MP and shows them in sku moderation (unmapped tab).
Later, a seller can map the sku's from this map.
2): Moderate and Map
This mode pulls the catalog from the MP and then map all the channel sku's with the E retail sku in case they are same.
The rest of the unmapped skus which are not having the same skus gets reflected in the sku moderation (unmapped tab).
3) : Create
If a client is having the unique skus on all the channels and he requires to get them created on the e retail panel then the system can pull all the skus from the MP and can get them created in the system with a default HSN.