6.4.3.4. Element Set Name

The Z-server creates a result set in response to a query. The result set is a set of pointers to records in one or more databases. An element set name identifies a group of elements in a database record for the Z-server to return to the Z-client. The CIMI Profile defines the following three element set names for the Abstract Record Structure for the Retrieval Record (element set names are literal strings):

• b
• mb
• f

6.4.3.4.1. Element Set Name b

The element set name b (i.e. brief) is intended to retrieve a form of the database record comprised of tagSet-G elements at the top of the Abstract Record Structure for the Retrieval Record. Retrieval of this form of the record corresponds to a generic level of resource discovery and retrieval utilizing the Dublin Core Metadata Elements. See Section 6.6. Conformance. Other tagSet-G and tagSet-M elements can be included by the Z-server in the retrieval record. The following elements comprise element set name b:

6.4.3.4.2. Element Set Name mb

The element set name mb is intended to retrieve a brief form of the database record according to common practice in museum systems (i.e., a museum brief record). The purpose of this brief form is to provide CIMI Z-clients with sufficient data elements to construct a tombstone record.

If the described resource has one or more associated images, Z-servers may include one or more mrObject elements and associated rendition elements for each image available. Servers will send details of all available images and image renditions in element set name mb. Occurrences of rendition should be ordered in increasing resolution, with lowest/smallest rendition occurring first.

The Z-server may include tagSet-G and tagSet-M elements in the retrieval record.

* include subelements for mrObject per Abstract Record Structure as warranted

6.4.3.4.3. Element Set Name f

The element set name f (i.e., full) includes all available database record elements. Those database record elements that can be tagged using the available tags from tagSet–G, tagSet–M, tagSet–Collections, and tagSet–CIMI should be so tagged. Additional elements returned by the server should be packaged into the element displayObject, or the Z-server can use TagType 3 with string tags for locally defined elements. The client does not process the data in displayObject or string tags but simply displays the information to the user.

6.4.3.4.4. Guidance for the Retrieval Record

The following is implementation guidance for a CIMI Z-server's behavior when no field exists in a database for an element requested in an element set name.

The following are the three possible cases:

• A field exists in the database and contains data
• A field exists in the database but contains no data
• No field exists in the database.

The first case presents no problem. The CIMI Z-server returns a GRS element(s) with the appropriate data.

For the second case, the CIMI Z-server returns the GRS element and for ElementData returns elementEmpty. This explicitly tells the CIMI Z-client that there is no data in the field.

In the third case, the CIMI Z-server may respond in two ways:

• The CIMI Z-server returns the GRS element and for ElementData returns elementNotThere. This explicitly tells the CIMI Z-client that there is no database field in the record.
• The CIMI Z-server does not return the GRS element.

The CIMI Z-client will interpret these two CIMI Z-server responses in the same way, namely, that there is no database field in the record associated with the GRS element.

6.4.3.5. Record Syntaxes

The CIMI Profile requires the support of the following record syntax defined by Z39.50-1995:

• GRS-1, Generic Record Syntax (OID = 1.2.840.10003.5.105)

For interchange, GRS-1 records are to be treated as the complete and canonical representation.

For purposes of interoperability, servers may support other record syntaxes including:

• USMARC (OID = 1.2.840.10003.5.10) -- an implementation of ANSI/NISO Z39.2 [9] which is maintained by the Library of Congress [13]
• SUTRS, Simple Unstructured Text Record Syntax (OID = 1.2.840.10003.5.101) -- defined in Z39.50.

The recommendations on supporting the USMARC record syntax can be found in Section 6.6. Conformance.

When a server is unable to return an object in the requested record syntax, the server should return a diagnostic (e.g., Bib-1 Diagnostic #238 - Record not available in requested syntax; Bib-1 Diagnostic #239 - Record syntax not supported).

6.4.3.5.1. Use of GRS-1

Usage of record syntax GRS-1 is defined as follows. In the GRS-1 main structure, the following parameters must be supported:

tagType
tagValue
tagOccurrence
content
appliedVariant

The GRS-1 element appliedVariant may be used in retrieval record elements including:

• displayObject
• resource

The following defines how appliedVariant is used with each of these elements

Variant information for displayObject
Variant information may be supplied for displayObject. If no variant information is supplied, the content of the element is assumed to be text.

Variant information for resource
Variant information is provided to indicate the type and size of the "image." Type is conveyed through a MIME-type value. Size is conveyed through the use of a string value or actual size in intUnit.

The server uses the following appliedVariant when the content of the element resource is a pointer to the image:

To provide information about the MIME-type of the image:

To provide information about the size of the image using an enumerated set of string values:

Allowable string values for the variant description that addresses the size of the image are:

• thumbnail
• wallet
• snapshot
• standard
• other

To provide information about the actual size of the image:

Unit is defined as (see http://lcweb.loc.gov/z3950/agency/defs/units/zunits.html)

• unitSystem = Z3950
• unitType = information unit
• unit = byte

To provide information about the cost of the image:

Unit is defined as (see http://lcweb.loc.gov/z3950/agency/defs/units/zunits.html)

• unitSystem = Z3950
• unitType = iso4217-1990
• unit = currency code from ISO 4217-1990

6.4.3.6. Retrieval of Images

The CIMI Profile, Release 1.0., does not address encoding of images (or other binary data) directly in GRS-1 for retrieval via Z39.50. The assumption is that CIMI Z-servers will provide CIMI Z-clients information about available images associated with object records and available renditions of those images. The repeatable element rendition contains a subelement resource that will contain a HTTP URL or the actual bit stream of data for a specific rendition of an image.

This CIMI Profile provide the following guidance regarding the sizes of images that CIMI Z-servers may provide to CIMI Z-clients:

• thumbnail: maximum size 96x96 (corresponds to PCD Base/64)
• wallet: maximum size 192x192 quarter screen (corresponds to PCD Base/16)
• snapshot: maximum size 384x384 (corresponds to PCD Base/4)
• standard: maximum size 768x768 (corresponds to PCD Base)
• other: dimension not specified.

Renditions are to be ordered in the GRS record with the smallest size/lowest resolution listed in the first occurrence of rendition. A CIMI Z-client, however, should look at the appliedVariant information for resource to determine if the rendition is an appropriate size for its use.

6.4.4. Close

The CIMI Profile requires clients and servers to recognize the Close protocol data unit (PDU), but the actual use of the Close Service is optional.

6.5. Diagnostic Messages

The Implementors Agreement requires support for Diagnostic Set Bib-1 (OID = 1.2.840.10003.4.1).

CIMI Z-servers will support the diagnostic 1024: Unsupported Attribute. This diagnostic will be used with addInfo, which will include an unstructured string indicating the object identifier of the attribute set id, the numeric value of the attribute type, and the numeric value of the attribute.

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