MODEL RELEASED. Medical records. Nurse using a hand-held bar code scanner which is linked to a computer. The scanner is reading the bar code on an adhesive label which can be attached to a tissue sample or patient records. Bar codes are comprised of a series of black, parallel lines. The scanner's head reads the bar codes by sending out a beam of light and monitoring the reflections. The bar code is then converted into digital data and stored on a computer. Photograph of a midwife nurse in Tameside Hospital, Great Britain.