D404 Nucleic Acids Research, 2008, Vol. 36, Database issue to the STAR (Self-deﬁning Text Archival and Retrieval) speciﬁcations deﬁned by Hall and coworkers (20–22). The PDB exchange dictionary used by the RCSB-PDB to drive the ADIT deposition system and to construct mmCIF ﬁles (23,24) is another application of the STAR speciﬁcation. The NMR-STAR data model contains over 4600 deﬁned data tags organized into more than 300 categories and 80 category groups. Data deﬁned by category groups represent real objects such as molecular assemblies, molecular entities (polymers and non-polymers), samples and sample conditions, NMR experiments, chemical shift referencing and many kinds of NMR spectral data and derived data (assigned chemical shifts, coupling constants, relaxation parameters, etc.). NMR-STAR and the derived NMRIF (NMR information ﬁle) are compatible with the PDB exchange dictionary and extend the data model to include information relevant to biological NMR spectro- scopy. NMR-STAR is extensible and can accommodate the addition of new NMR parameters of interest to the biomolecular NMR community (recent additions have included solid-state NMR and information from NMR experiments on metabolomic standard compounds). The tag-value nature of the NMR-STAR format and tabular organization of the NMR-STAR data model make it easy to create a corresponding relational data model or XML format. CONTENT AND ACCESS Assigned chemical shifts Assigned NMR chemical shifts constitute the bulk of the data submitted by depositors directly to BMRB. The ﬁrst BMRB entries ( 1200) were constructed by annotators from data extracted from journal publications. Nearly all BMRB entries released since 1996 are the result of author depositions. The archive now contains over 4400 entries representing more than 2.5 million chemical shifts for individual proteins, peptides, DNA and RNA molecules, and a variety of macromolecular complexes. BMRB provides statistical tables containing the mean, minimum, maximum and standard deviation for the reported chemical shifts for each 1H, 13C, 15N and 31P atom found in the common amino and nucleic acids. These tables provide results both from the full BMRB archive and also from the subset of the archive that is believed to represent diamagnetic molecular systems ﬁltered to remove suspected erroneous chemical shift values. Additional tables provide lists of chemical shifts that fall outside 3 SD from the mean for each atom in the 20 common amino acids. These shifts are often of great interest and are linked to the source entry to allow users to quickly determine the type of molecular system involved. For those interested in obtaining lists of chemical shifts for a particular atom from any of the common biopolymer residues (protein, DNA or RNA), a query system is provided that will generate either an HTML page or a tab- delimited ﬁle that can be downloaded for further analysis. The BMRB Query Grid Interface (http://www. bmrb.wisc.edu/search/query_grid/initial_grid.html) can be used to perform a number of common queries. Examples are: (i) select entries with molecular systems containing proteins, DNA or RNA; (ii) select protein only entries; (iii) select entries with matched PDB entries; (iv) select protein entries that reported the use of IUPAC recommended chemical shift referencing (17) and (v) select protein entries containing at least one reported ligand (metal ion and/or organic compound). The Query Grid Tool also can be used to locate BMRB entries that contain other kinds of NMR spectral or derived data including, coupling constants, T1, T2, heteronuclear NOE and order parameters, residual dipolar couplings and hydrogen exchange rates. From the ‘Search Archive’ page (http://www.bmrb. wisc.edu/search/), individual entries can be retrieved by BMRB accession number, BMRB deposition code or a related PDB code. Other query tools located on the page allow users to search the archive for entries by particular author, biopolymer name, range of pH or temperature and BMRB or PDB accession code (http://www. bmrb.wisc.edu/cgi-bin/nmrbrowse.cgi). A FASTA search engine allows entries to be retrieved on the basis of sequence relatedness to a query sequence. The DEVise data visualization tool (25,26) has been integrated into the BMRB website as both a query tool and a presentation tool for data in or derived from individual entries. The system provides web-based inter- active plots for a wide variety of data either as individual plots or as multiple plots linked to a 3D structure (data derived from PDB). DEVise histogram visualizations of chemical shift data for selected amino acid atoms can be used to locate outlier chemical shifts; a shift-click on a bar in the histogram retrieves a list of the entries containing the chemical shift values that contribute to the bar. Hyperlinks allow direct access to the entries. The user can select whether the histogram visualizations utilize statistics from the full database or from the ‘diamagnetic’, ﬁltered database. For individual entries depending on data availability, plots can be chosen that display the chemical shift index (CSI) (27,28), the experimental chemical shifts versus CSI delta, coupling constants, heteronuclear NOEs, T1 values, T2 values or order parameters. In cases where a BMRB entry can be matched to a PDB entry, these plots are combined with an interactive 3D Jmol (http://www.jmol.org/) model of the structure. The data plots and 3D image are linked, making it possible to easily visualize the residues in the structure that have the data characteristics selected from the plots (Figure 1). For entries that contain 13C chemical shifts for amino acid Ha, Ca and Cb atoms, LACS (19) visualizations are available that provide a statistical identiﬁcation of outlier chemical shift values and an indication of the correctness of the chemical shift referencing used in the entry. Restraints The NMR derived restraints used to calculate 3D models of biological macromolecules are the key to understanding the quality of the reported structures. In the past, the restraints ﬁles available from the PDB depositions were not annotated with respect to the deposited coordinates and the restraint data were present in a variety of formats