IUCLID features four different layers to store data, each serving a distinct purpose, and each containing (filtered, frozen) data from the one above.
Data can be copied from one layer to another by several dedicated application functions, e.g.:
"Import an XML File" copies data from the XML layer to the dossier or raw data layer
"Export an XML File" copies data from the raw data or dossier layer to the XML layer
"Create Dossier" copies data from the raw data layer to the dossier layer
and so on...
Every data object is uniquely identified by a UUID, which stands for "Universally Unique Identifier". Basically, the intent of UUIDs is to enable distributed systems (like the thousands of IUCLID installations out there...) to uniquely identify information without significant central coordination. In the IUCLID context, the UUIDs also help to identify similar, newer or older versions of the same data object across data layers.
For example: a Substance in the raw data layer is identified by its UUID. This UUID remains the same even when the Substance is copied into the Dossier layer. When the Substance is later updated in the raw data layer, the IUCLID system can still make the connection between the "current" version of the Substance in the raw data layer and the "older" version in the Dossier layer.
All information is entered (either manually or as import) into the IUCLID raw data layer, which serves as the essential storage location for all data before they are further treated and handled (e.g. as Dossiers). All data in the raw data layer can be retrieved, updated, extended and deleted. All imaginable information foreseen in the IUCLID data model about a Substance (or Mixture) and other objects can be entered, totally independent of the legislation, programme or other purpose the data is later foreseen to be used.
From this all-encompassing information pool, selected data can be copied into another layer, e.g. as a Dossier (= a snapshot of a particular subset of raw data at a particular moment in time) or as a raw data export file (= an XML representation of parts of the raw data). The exact selection of which data are to be copied depends on the purpose for which the user creates the copy. (In the case of Dossiers, the selection will most probably depend on the legislation or programme for which the Dossier is prepared.)
Technical Information:
The "Dossier UUID" (displayed in the information panel) for raw data is always "0".
The dossier layer contains read only data, i.e. no Dossier can ever be changed after its creation; the dossier layer can therefore be considered as a frozen subset of the raw data, each dossier being a snapshot of a particular object (a Substance, a Mixture, ...) of the raw data.
In the dossier layer, only the following data manipulation operations are possible:
Create a whole Dossier
Import a whole Dossier
Delete a whole Dossier
Therefore, if a dossier has to be modified, it has to be deleted, the data have to be updated in the raw data layer, and the dossier has then to be re-created from the modified raw data. This ensures that updates always happen where the "live" data are located, i.e. in the raw data layer, and that dossiers do not start deviating from their source.
Technical Information:
Each Dossier has a unique identifier. The "Dossier UUID" (displayed in the information panel) identifies the Dossier data object (e.g. an Endpoint study) is assigned to.
If multiple Dossiers are created from the same Substance, the Substance is stored multiple times in the dossier layer.
Annotations can be attached to all data objects, both in the raw data layer and in the dossier layer, and are stored in the separate annotation layer. Annotations always need a parent object (a substance, end endpoint study record, etc.) and cannot exist without one.
If a data object (e.g. an endpoint study record) or a dossier is deleted, all related annotations are therefore also deleted.
Technical Information:
Each annotation has a unique identifier "Record ID", displayed in the information tab of the annotation window. The second part of the Record ID for annotations is always "/0" because an annotation can not be frozen into a dossier.
Each annotation is linked via the "Linked record ID" to a data object (e.g. an endpoint study record). The "Linked record ID" is a concatenation of the UUID / dossier UUID (e.g. IUC4-bfa610ea-fe3c-36b3-8fa2-6faf50bbe66c/0).
Both raw data and dossier data can be exported from IUCLID into a (collection of) XML file(s). This is useful in situations like:
Submission of Dossiers to regualtory authorities (Dossiers must be submitted in the XML format).
Exchange of data between two or more IUCLID installations.
Exchange data between IUCLID and a third party application.
IUCLID exchange files have the extension .i5z.
Every i5z file is in fact a zipped (archived) collection of XML files (with the .i5d extension)
Technical Information:
The unique identifier (UUID) is also used in the exchange layer. Inside the i5z container the UUIDs are used as unique files names.