To fully and accurately characterize the IUE dataset and facilitate future analysis, a group of ``core data items'' descriptive of each image was identified. These core data items (CDIs) are defined as all parameters related to the acquired images which are either necessary for image processing with the NEWSIPS system or for scientific analysis of the data. This chapter identifies and defines each CDI, indicates valid values for the CDI, the sources used to verify the CDI, and any comments relevant to the use of the CDI.
The CDIs are of two types: input and output CDIs. All input CDIs for each image are verified for accuracy before NEWSIPS processing of the image by the IUE Project. Images are verified at the acquiring observation station. Sources for verification of the CDIs include the original observing script at GSFC and the observing log at VILSPA, the original VICAR image label, engineering data, and handwritten records. The output CDIs are generated by the NEWSIPS processing.