Mandatory metadata

Certain metadata contained in NeXus files are common to all DESY experiments, the mandatory metadata (MMD). The size of the MMD is small. But they are sufficient for a rough identification of the file contents. Besides, MMD are used by the ingestion procedure inserting files into the metadata catalogue.

Table 9.1: Mandatory metadata
NeXus field or attribute ICAT field Remark
/NXentry/experiment_identifier Investigation a unique beamtime IT
/NXentry/title Investigation.Summary description of the experiment
/NXentry/NXinstrument/name Instrument.Fullname name of the beamline
/NXentry/NXinstrument/name@short_name Instrument.Name short name of the beamline
/NXentry/NXinstrument/NXsource/name Facility.Fullname accelerator name
/NXentry/NXinstrument/NXsource/name@short_name Facility.Name short name for the accelerator
/NXentry/NXsample/name Sample.Name name of the sample
/NXentry/NXsample/chemical_formula Sampletype.Molecularformula the sample chemical formula
/NXentry/start_time Instrument.Start_Date start time of the scan
/NXentry/end_time Instrument.End_Date end time of the scan

Table 9.1 contains a list of the DESY MMD and it shows how the NeXus items are mapped to ICAT fields.