Metadata is stored in MAGE-TAB format
Each experiment is represented by two MAGE-TAB spreadsheets: the Investigation Description Format (IDF) file and the Sample Data Relationship Format (SDRF) file (Figure 4).
Figure 4 Representation of experiment metadata in Investigation Description Format (IDF) and Sample Data Relationship Format (SDRF) spreadsheets.
The two main MAGE-TAB spreadsheets
The IDF contains an overview of the whole experiment, including the title, the submitter's contact details, publication information, protocols and the experimental variables.
The SDRF describes all the sample characteristics (e.g. cell type) or any treatment that the sample has been subjected to (e.g. growth in low oxygen conditions), and links each sample to its corresponding data file. The structure of the SDRF, i.e. the order of the columns, reflects the experimental workflow from source material, through intermediate steps (e.g. labelling of nucleic acids, preparation of sequencing libraries, running of sequencing assays) to raw and processed data.