Aspects of a topic are conveyed by (in order of preference when available)

• Pre-coordinated descriptors
• Descriptor/qualifier (Main heading/subheading) combinations
• Multiple descriptors

Pre-coordinated Descriptors vs. Qualifiers

• To convey the concept of surgery of the liver you would need to use the descriptor Liver plus the qualifier surgery

• To convey the concept of surgery of the biliary tract you would use the pre-coordinated descriptor Biliary Tract Surgical Procedures

Pre-coordinated Descriptors vs. Multiple Descriptors

• Multiple descriptors may be needed to convey a concept
  • For the concept of “research in occupational therapy” you would use two descriptors:
    Occupational Therapy
    Research
  • However, for the concept of “research in nursing” you use only the pre-coordinated descriptor:
    Nursing Research