NRE/VDX uses Z39.50, an international industry standard that specifies a structure for searching and retrieving information from remote databases.
It refers to the International Standard, ISO 23950: Information Retrieval (Z39.50): Application Service Definition and Protocol Specification, and to ANSI/NISO Z39.50. If you are interested in learning more about Z39.50, visit the Library of Congress Z39.50 website.
Although Z39.50 is an international standard, there is a great deal of variation in how it is implemented. Different information providers may support different versions of the standard, or they may support some but not all of the possible attributes. For example, a provider may support Keyword searches, but not Subject searches.
When searching with Z39.50, your search results will vary depending on which attributes you search and whether or not the collection (library) you are searching supports the same attributes.
NRE/VDX provides you with 2 search interfaces, a standard search and an advanced search. The Z39.50 search is accessed using the BibSearch option in the menu bar on the left of the screen.