Medical Subject Headings
Entry Terms and Other Cross-References
1. Entry Terms
Entry terms, sometimes called "See cross-references" in printed listings, are synonyms, alternate forms, and other closely related terms in a given MeSH record that are generally used interchangeably with the preferred term for the purposes of indexing and retrieval, thus increasing the access points to MeSH-indexed data. Entry terms range from variations in form such as Heart Arrest and Arrest, Heart to substantial synonyms such as Heart Arrest and Asystole. Entry Terms are displayed as the Entry Term in the MeSH Browser, and exist as the <Term> element in XML MeSH. In the printed MeSH, the entry term is listed alphabetically, for example:
Abscess, Abdominal see Abdominal Abscess
In printed MeSH the entry term is also listed under the referred-to record and labeled "X" (as a "backwards cross-reference"):
Abdominal Abscess X Abscess, Abdominal
Note that only a subset of all entry terms are available in printed MeSH. See the PrintFlagYN attribute of terms in XML MeSH.
Entry terms are not always strictly synonymous with the preferred term in the record or with each other. However, for the purpose of organizing the NLM-indexed literature, fine granularity is not always required, so the entry terms are equivalent to the preferred term for purposes of indexing and retrieval. Note, however, XML MeSH does identify strict synonymy between subsets of terms within a record. See the <Concept> element in XML MeSH and Concept Structure in XML MeSH Data.
2. Other cross-references
Three kinds of informative references suggest other Descriptors in MeSH that relate to the subject and that may be useful in indexing, cataloging, or searching a particular topic.
2.1 See Related
See related references, also known as "associative relationships" are used for a variety of relationships between Descriptor records where a user of one Descriptor is reminded of another Descriptor which may be more appropriate for a particular purpose. For example, the relationship may be between a disease and its cause:
Factor XIII Deficiency see related Factor XIIIa
Or between an organ and a physiological process :
Bone and Bones see related Osteogenesis
Or between an organ and a drug acting on it :
Bronchi see related Bronchoconstrictor Agents
Or between an organ and a procedure:
Bile Ducts see related Cholangiography
In printed MeSH the see related reference also listed as under the referred-to entry and labeled "XR" (as a "backwards see related cross-reference"):
Cholangiography XR Bile Ducts
In the MeSH Browser the See Related reference is displayed as See Also, and is the <SeeRelatedDescriptor> element in XML MeSH. For further discussion see Relationships in Medical Subject Headings.
2.2 Consider Also
Reference to other Descriptors having related linguistic roots, for example:
Brain consider also terms at CEREBR- and ENCEPHAL-.
The Consider Also reference is used is primarily with anatomical Descriptors to refer to groups of Descriptors beginning with a common stem rather than to a single Descriptor. In the MeSH Browser the reference is displayed as Consider Also, and as the <ConsiderAlso> element in XML MeSH.
2.3 Entry Combination
In some NLM systems using MeSH, certain Descriptor/Qualifier combinations are prohibited by a special MeSH data element called the <EntryCombination> in XML MeSH, and Entry Combination in the MeSH Browser. For example, the Descriptor Accidents cannot be used with the Qualifier prevention & control, but instead of this combination, the Descriptor Accident Prevention should be used. In the printed MeSH this information appears under Accidents as:
Accidents/prevention & control see Accident Prevention.
The subject thought to be expressed by Accidents/prevention & control is equivalent to the actual MeSH Descriptor Accident Prevention.
2.4 MeSH Tree Structures
In some thesauri the function cross references to broader and narrower terms is comparable to the hierarchical relationships in the MeSH Tree Structures, though hierarchies enable multiple levels of specificity, as do the MeSH Trees. These relationships are displayed graphically in the MeSH Browser and printed MeSH. The Trees data are also used by PubMed for the default behavior of inclusive searching. The Trees data in XML MeSH are to be found in the TreeNumber element.