The LLS, Logos Library System, ebook viewing technology was developed by Logos Research Systems. This technology is used in the company's Logos Bible Software Version 2 and in software and ebook products from other companies and publishers. LDLS, Libronix Digital Library System, is the next generation technology after LLS and used in the Logos Bible Software Series X.
Logos's viewer technology is distinguished by a fuller implementation of the library concept as compared to the single book functionality of many ebook viewer systems. Multiple books can be browsed, opened, searched, and linked in the Logos viewer program. LDLS takes the library concept even further than LLS. For example, LDLS allows books to be sorted according to the title, author, or subject fields of the book's MARC record (MAchine-Readable Cataloging record), thus mimicking the standard cataloging system used by libraries.
Logos's viewer technology was also developed with special attention to the needs of students of the Bible. Bible versions and commentaries can be synchronized by chapter and verse. Bible references in non-biblical books are hypertext linked to Bibles.
LLS ebooks are constituted of two computer files with the file extensions lix and lsf. LDLS ebooks have only one file with the file extension lbxlls. LLS ebooks can be read in LDLS-based viewer programs (such as Logos Bible Software Series X), but LDLS books do not function in LLS-based programs.
Read more about Libronix Digital Library System: www.logos.com/products/ldls
LDLS viewer: www.logos.com/support/downloads/ldls
Rose Tree Press ebooks in LLS format have been discontinued. eBooks in LDLS format are not available at present.