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Union catalog of digital resources

Why select this database?

  • Contains digital resources from open archive collections
  • Represents multidisciplinary resources from more than 1,100 contributors worldwide
  • Records contain a digital object link allowing users access to the object in a single click

Subjects included

Digital resources including:

  • Digitized books and articles
  • Born-digital texts
  • Audio files
  • Images
  • Movies
  • Datasets

Collections including:

  • Theses
  • Technical reports
  • Research papers
  • Image collections

Database details

Database name OAIster
Short database name OAIster
Available on FirstSearch, WorldCat Discovery, and
Sources 2,000+ data contributors
Number of records More than 50 million records
Update frequency Quarterly
Producer OCLC Online Computer Library Center, Inc.


Index labels and search examples

Use a colon after an index label (for example, au:) when you are not certain of your search terms. Use an equal sign after an index label (au=) for an exact match search. You can search with an index label from any search screen. The information you type overrides any default menu selections. The following examples show sample rather than actual searches.

Search indexes Labels Examples
Keyword kw: predecessor institutions
Access method am: http
Accession number no: AIM25_2229
Author au: wessels
Author phrase au= wessels martin

[last name first]
Content type ct: text
Data contributor dc: area aim 25
Data contributor phrase dc= archives in London and the m25 area aim25
Language phrase ln: English

[use to refine other search terms]
Notes nt: university archivist
Publication date pd: 20050407
Publisher pb: university surrey guildford
Resource format fr: html
Resource type phrase ry= image
Source so: gender behavior
Subject su: mathematics
Subject Phrase su= mathematics statistics
Title ti: contact networks
Title Phrase ti= modeling protein contact networks
Year yr: 2007

Index use and structure

What follows is a list of FirstSearch indexes and the combination of USE and STRUCTURE attributes that can be used to access them.

  1. For any FirstSearch label where multiple USE attributes are listed, all the attributes will provide the exact same search result sets
  2. Any USE attribute that is not marked as a restrictor is available via the SCAN service.
  3. Restrictors are specially implemented indexes and are not available for scanning. Terms for these must be ANDed with other terms to limit the size of the result set. See the table provided for each restrictor to determine valid terms and their associated meaning.

FirstSearch Indexes and USE and STRUCTURE attributes used to access them

Index Description Use Attribute Structure Attribute Indexed Data Source
Keyword (kw) Any 5110 2 245/a







Keyword All (ka) Any 1016 2 100/a








Access Method (am) OCLC Defined 5856 2 856/u
Accession Number (no) Control number-local 12 2 035/a
Author (au) Author-name 1003 1,2 100/a

Content type (ct:) Content-type 1034 1 598/b
Data Contributor (dc, dc=) OCLC Defined 5076 1,2 902/g
Language Phrase (ln=)* Code-Language 54 1 546/a

Notes (nt) Note 63 2 500/a



Publication Date (pd) Date 30 2 260/c

Publisher (pb) Name-publisher 1018 2 260/b
Source (so) Title-host-item 1033 1,2 773/g
Subject (su, su=) Subject 21 1,2 650/a

Title (ti, ti=) Title 4 1,2 245/a
Year (yr)* Date-publication 31 2,4,5 964/x,y

* Language and Year also serve as restrictors when they are not the first term in a search.

Record display information

The MARC records returned from this database will be the OCLC-MARC records as they were input into the system.

This database can have any valid MARC tag in it. Besides the valid MARC tags, the following FirstSearch Locally Defined fields also exist:

856 fields

OCLC has added links to additional content such as cover art, table of contents, summaries and author notes. These OCLC-created 856 fields include the following subfields:

856/u URL to additional content

856/i Instructions in URL use

856/q Data type such as "ASCII," "GIF," etc.

856/x "OCLC EC"

856/3 Type of content such as "COVER ART," "TABLE OF CONTENTS," "MORE INFO," or "EXCERPTS"

Evaluative content info in websites: OCLC created URLs contained in 856/u fields in full MARC syntax and under the label "Access:" in full SUTRS syntax will allow internet-based access to evaluative content (cover art, summaries, excerpts, author information, etc.) These URLs can be cut and pasted, or programmatically entered, into any browser supported by FirstSearch in order to gain access to the information. The URLs will time out after 7 days so if continued access is desired another search to receive and updated URL will need to be executed. The 856/i field is the indicator for information on the URL; because not all 856/u fields are additional evaluative content, the 856/i should be checked to be certain the 856/u link is truly a OCLC sourced link. The 856/i field contains instructions regarding the URL.

NetLibrary websites: All NetLibrary records have had additional 856 fields added that would authenticate a user's access to their library's NetLibrary book subscription, based on their FirstSearch authorization number. These 856 fields will have a subfield u with the URL and a subfield I with the instructions:

"Input this URL in a browser to view e-book from NetLibrary."

Note: Searching "NetLibrary" in the Access Method index can retrieve all NetLibrary books. All NetLibrary books that a FS user subscribes to can be searched by ANDing this to the library's holding symbol, assuming the library is cataloging their holdings on the OCLC WorldCat cataloging subsystem.

945/f Primary document type code
945/d Additional document type codes
945/m Material type code media/technology access
945/n Material type text media/technology access
945/p Material type code content
945/q Material type text content
945/r Music Composition code
945/s Music Composition text
947/g Displayable form of the LC Control Number [010/a]
947/h Displayable form of the LC Control Number [010/z]
947/m Number of holding library symbols connected to item
947/n Date added to a database
947/p Date last updated in Cataloging subsystem of WorldCat
947/s Indicator for My Library holdings.

This indicates if authorization number's institution has local holdings attached in OCLC WorldCat. "Y" is yes. "N" is no.

Library Holdings

Field 948/a gives the ISO country code information for each library holding the item. Additional detailed holdings information is available in FirstSearch Z39.50 Configuration Guide - Element Set Names Available.

949/i Document Types (repeating)

a = Articles, Chapters, or Papers

b = Books, Monographics, or Text

f = Visual Material

h = Maps

i = Computer File

j = Sound Recording

k = Score

m = Archival Material

r = Continually updated resource

s = Serial, Journal, or Magazine

w = Internet Resources, primarily websites
949/x ILL/Display type

b = Books, Monographic, or Text including articles and websites listed as text

f = Visual Material

h = Maps

l = Computer File

j = Sound recordings

k = Score

m = Archival Material

s = Serial, Journal, or Magazine

g = Multiple types, includes more then one of the types listed above)


The following restrictors can be used only in conjunction with an index search. They must be added to an index search with the Boolean AND in order to receive results.

Restrictor Type Input Use Attribute Structure Attribute
Resource type Phrase** No Limit










1001 1
Language** No Limit




54 1
Year** No Limit

Single: 19xx

Range: 19xx-20xx

19xx, 20xx

31 5

** Resource Type Phrase, Language, and Year are all both indexes and restrictors.


Search results in the OAIster database can be sorted by Author (1003), Title (4), Date (30) and Source Title (1033).

General punctuation rules

Omit accent marks and diacritics such as umlaut (¨) and cedilla (¸). Special characters should be replaced by a Romanized form of the character, such as u for hooked u and ss for eszett (ß).

Punctuation Rule Punctuation Rule
" (quote mark) Convert to a blank @ (commercial at) Convert to a blank
' (apostrophe) Indexed both as:

— delete and collapse

— convert to a blank
? (question mark) Convert to a blank
. (period) Convert to a blank, except when the first period in a class number search. / (slash) Convert to a blank except in Dewey call number search where it is deleted and collapsed.
, (comma) Convert to a blank. - (hyphen) Convert to a blank
; (semicolon) Convert to a blank & (ampersand) Retain and index
: (colon) Convert to a blank \ (backslash) Convert to a blank
() (parentheses) Delete and collapse © (copyright sign) Delete and collapse
<> (greater/less than signs) Convert to a blank ° (degree sign) Delete and collapse
{} (curly brackets) Convert to a blank € (Euro) Convert to a blank
[] (square brackets) Delete and collapse, retaining the data within except for [sic] and [i.e. any data following] Flat (musical) Convert to a blank
= (equal sign) Convert to a blank ¡ (inverted exclamation point) Convert to a blank
! (exclamation point) Convert to a blank ¿ (inverted question mark) Convert to a blank
# (number sign) Delete and collapse Phonograph copyright Delete and collapse
$ (dollar sign) Convert to a blank # (sharp — musical) Convert to a blank
% (percent sign) Convert to a blank Space Convert multiple spaces to a single space
* (asterisk) Convert to a blank ± (plus/minus sign) Convert to a blank
+ (plus sign) Convert to a blank _ (underscore) Convert to a blank

Searching tips

Keyword All searches (1016): The Keyword All search includes elements from the Abstract, Author, Title, Subject, Source Phrase, and Note indexes.

Using restrictors: English and Non-English are restrictors. All other language terms can be searched alone in the Language (54) index.

Using limiters: Use the following indexes as limiters to an index search in order to narrow the focus of your search: Document Type (1001) and Content Type (1034). OCLC uses these indexes as limiters on the web.

Copyright information

OAISTER was originally developed at the University of Michigan Libraries with the support of a grant from the Andrew W. Mellon Foundation.