Understanding the Z39.50 Standard

The question asks us to identify the true statements regarding the Z39.50 standard. Z39.50 is an international standard that defines a protocol for computer-to-computer information retrieval.

Let's examine each statement provided:

Analyzing Statements about Z39.50

• Statement A: It is an international (ISO 23950) standard

This statement is true. Z39.50 was developed in the United States as an ANSI/NISO standard. It was later adopted as an international standard, ISO 23950, making it recognized and used globally for searching databases.

• Statement B: The contextual Query Language is not based on Z 39.50 semantics

This statement is false. The Contextual Query Language (CQL) is a query language specifically designed for information retrieval and is, in fact, based on the semantics of Z39.50. CQL aims to be more intuitive and human-readable than the original Z39.50 query syntax, while retaining its power and flexibility for complex searches across different databases.

• Statement C: It was originally approved by the National Information Standards Organisation (NISO) in 1988

This statement is true. The Z39.50 standard was initially developed and approved by the National Information Standards Organization (NISO) in the United States, with its first version being approved in 1988. NISO plays a key role in developing and maintaining standards for information systems.

• Statement D: It is maintained by IFLA

This statement is false. While the International Federation of Library Associations and Institutions (IFLA) promotes standards in the library world, Z39.50 is primarily maintained by the Library of Congress in conjunction with NISO in the United States. International collaboration exists, but IFLA is not the official maintenance body.

Conclusion on Z39.50 Facts

Based on the analysis of each statement:

• Statement A is true.
• Statement B is false.
• Statement C is true.
• Statement D is false.

Therefore, the statements that are true about Z39.50 are A and C.

Evaluating the Options

Let's compare our findings with the given options:

• Option 1: A and B only (Incorrect, B is false)
• Option 2: A and C only (Correct, A and C are true)
• Option 3: B and C only (Incorrect, B is false)
• Option 4: C and D only (Incorrect, D is false)

The option that correctly identifies the true statements is A and C only.

Revision Table: Z39.50 Standard

Additional Information on Z39.50 and Related Standards

Z39.50 is a client-server protocol. This means a Z39.50 client software sends queries to a Z39.50 server software, which then searches its database (like a library catalog) and returns results in a standardized format. This allows users to search multiple databases using a single interface, without needing to know the specifics of each database system.

Some key concepts related to Z39.50 include:

• Attribute Set: Defines the meaning of search terms (e.g., searching by title, author, subject). The commonly used set is Bib-1.
• Record Syntax: Defines how the results are formatted (e.g., MARC 21, MODS).
• Contextual Query Language (CQL): As mentioned, a standard syntax for representing queries, designed to be clearer than the original Z39.50 Type-1 query. It evolved from Z39.50 principles.

While Z39.50 was foundational for federated searching, newer protocols and technologies like SRU/SRW (Search/Retrieve via URL/Web Service), OAI-PMH (Open Archives Initiative Protocol for Metadata Harvesting), and web-based APIs are also used for information retrieval and metadata exchange in modern systems.