The Crossref Curriculum

Secondary queries

The Crossref query engine operates by processing many different rules. By default, all metadata provided in a query is used to generate a match, and a result is only returned if exactly one DOI match is found. Enabling a secondary query instructs the query engine to perform specific searches when the initial search fails to find a match.

Author/article title secondary query

Queries by default use all metadata present in the request. Requests with only an author and title are treated as author/article title queries. When other fields are present, the request is submitted as a metadata search.

Setting the secondary-query attribute to author-title causes an author/title search to be performed when the initial metadata search fails to find a match.

<query key="cit-3" enable-multiple-hits="true" secondary-query="author-title">
<issn>0360-3016</issn>
<volume>54</volume>
<issue>2</issue>
<first_page>215</first_page>
<year>2002</year>
<author>Kim</author>
<article_title match="fuzzy">Potential radiation sensitizing effect of SU5416 by down-regulating the COX-2 expression in human lung cancer cells</article_title>
</query>

Year is included in the author/article title secondary query when present. An author/article title query will only be performed if both author and article title are included in the query.

Multiple hits secondary query

By default, the query engine will only return a result if a single DOI is found. Queries returning multiple results (or hits) are unresolved. Setting the secondary-query attribute to “multi-hit” instructs the query engine to return all available results.

<query key="cit-3" secondary-query="multiple-hits">
<issn>0360-3016</issn>
<volume>54</volume>
<issue>2</issue>
<first_page>215</first_page>
<year>2002</year>
<author>Kim</author>
<article_title match="fuzzy">Potential radiation sensitizing effect of SU5416 by down-regulating the COX-2 expression in human lung cancer cells</article_title>
</query>

This option can also be performed by setting attribute enable-multiple-hits (learn more about allowing multiple hits) to true.

Author/title multiple hits secondary query

Setting the secondary-query attribute to “author-title-multiple-hits” instructs the query engine to perform an author/title query and return multiple hits if the initial search fails.

<query key="cit-3" enable-multiple-hits="true" secondary-query="author-title-multiple-hits">
<issn>0360-3016</issn>
<volume>54</volume>
<issue>2</issue>
<first_page>215</first_page>
<year>2002</year>
<author>Kim</author>
<article_title match="fuzzy">Potential radiation sensitizing effect of SU5416 by down-regulating the COX-2 expression in human lung cancer cells</article_title>
</query>

Secondary query results

Query results will specify which method was used to return the result. Successful metadata searches will specify metadata:

<query key="cit-3" status="multiresolved" fl_count="0" query_mode="metadata">

Queries resolved by the secondary author/title query will specify author-title:

<query status="resolved" fl_count="0" query_mode="author-title">

Queries with multiple hits will have a status of multiresolved

<query status="multiresolved" query_mode="metadata">

Last Updated: 2020 April 8 by Laura J. Wilkinson