Abdominal x-ray as a scout film for other procedures such as barium enemas. An upper gastrointestinal series is where a contrast medium, usually a radiocontrast agent such as barium sulfate barium salt mixed with water, is ingested or instilled into the gastrointestinal tract, and X-rays are used to create radiographs of the regions of interest. The barium enhances the visibility of the relevant parts of the gastrointestinal tract by coating the inside wall of the tract and appearing white on the film. A lower gastrointestinal series is where radiographs are taken while barium sulfate, a radiocontrast agent, fills the colon via an
Colon classification facets are generally associated with every item in a library, and so form a reasonably universal sorting system. As an example, the subject "research in the cure of tuberculosis of lungs by x-ray conducted in India in 1950" would be categorized as: This is summarized in a specific call number: The colon classification uses 42 main classes that are combined with other letters, numbers and marks in a manner resembling the Library of Congress Classification to sort a publication. CC uses five primary categories, or facets, to further specify the sorting of a publication. Collectively, they are called "PMEST": The