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Unified Medical Language System (UMLS)

LCH_NW (Library of Congress Subject Headings, Northwestern University subset) - Source Representation


This page lists specific source data elements and provides information on their representation in the UMLS Metathesaurus.


Skip to: Summary of Changes, Summary of Source-Provided Files Source-Provided File Details

Summary of Changes:


LCH_NW is a new source.

Source-Provided Files: Summary



All files are available here:  http://files.library.northwestern.edu/public/lcshmesh/

Additional documentation on the MARC 21 Format For Authority Data can be found here:  http://www.loc.gov/marc/authority/

Documentation:

File
Description
lcsh-mesh_read.doc Description of the project and files
lchs-mesh_sample.txt Sample data

Data:

File
Description
lcsh.mrc MARC 21 format authority file, with linking data to MSH strings

Source-Provided Files: Details



The data is provided as a MARC 21 format authority file.  Before Metathesaurus source processing, this file was converted to ascii using

file:  lcsh.mrc (converted to lcsh.mrc.txt):

Only the 010, 1XX (Heading Information) and 750 fields (Heading Linking Entry) were processed for inclusion in the Metathesaaurus. Other data such as 4XX (See From Tracing) and 5XX (See Also From Tracing) may be analyzed for inclusion in future versions.


MARC Tag/
Subfield
Description
Representation
010 $a
Library of Congress Control Number MRCONSO.CODE
MRCONSO.SCUI

MRMAP.FROMEXPR
010 $z
Canceled/invalid LC control number
Not included in Metathesaurus source processing



150, 151
$a
$x
$v
$y
$z
Heading - Topical Term, Heading - Geographic Name
name entry element
general  subdivision
form subdivsion
chronological subdivision
geographical subdivision
MRCONSO.STR
CODE = Value of tag = 010, subfield $a
TTY = PT
SUPPRESS = N

MRCONSO.STR is assembled by using "--" to concatenate the values of the $a, $x, $v, $y and $z subfields.



750 $a
Established Heading Linking Entry.

A 2nd indicator value of "2" indicates a MSH mapping.
MRREL.REL = RQ
MRREL.RELA = mapped_from

MRMAP.TOEXPR = SDUI of string of $a value

Note:  the original data in this field is populated by MSH strings.  Where possible, the strings have been translated to MSH identfiers.  In a small number of cases, the string provided did not correspond to a current MSH string, and these entries were dropped during Metathesaurus source processing.
$x
Indicates a MSH qualifier
MRMAP.TOEXPR = MSH SDUI values, in the format "Descriptor Identifier/Qualifier Identifier"
$8
field link/sequence number;  indicates that one LCH concept maps to two or more MSH entity MRMAP.TOEXPR = MSH SDUI values with the same sequence number, connected by "AND" 
MRMAP.TOTYPE = BOOLEAN_EXPRESSION_SDUI

MRMAP.MAPRANK is incremented if there is more than one grouping (i.e. if the sequence number is incremented).