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 (punctuation) of a list: while a double colon codice_3 is read as "has type of" (compare scope resolution operator): The ML languages (including Standard ML and OCaml) have the above reversed, where the double colon (codice_3) is used to add an element to the front of a list; and the single colon (codice_5) is used for type guards. MATLAB uses the colon as a binary operator that generates vectors, as well as to select particular portions of existing matrices. In Python, which uses indentation to indicate blocks, the colon is used in statements to indicate that the next line is the