Abstract: A computer implemented method of controlling release of a data product to a host, comprising: providing a data parcel to a host comprising: (i) a payload interpreter accessible by an interface application program interface (API) for operation by the host and (ii) a data payload readable by the payload interpreter comprising reference data describing at least one data product; accessing the data parcel with the interface API; enabling the data parcel in response to the data parcel being accessed with the interface API; and determining that the data parcel is enabled before allowing the host to operate the payload interpreter to read part or all of the data payload.