This document is meant to accompany FASTLINK, version 2.2 and beyond. It describes some aspects of the UNKNOWN program that is one of the auxiliary programs distributed with LINKAGE and FASTLINK. This material is a significant expansion of the discussion on pages 25-26 of Handbook of Human Genetic Linkage by Joseph Douglas Terwilliger and Jurg Ott. The emphasis there is on usage of UNKNOWN and all algorithmic aspects are suppressed. Here we focus on the algorithmic aspects after a brief excursion into usage. As with the documents on traversals and loops that first accompanied FASTLINK 2.1, this document is very informal and directed at those who may wish to modify the code.

Thanks to Jerry Halpern (Stanford) for suggesting that I prepare this document. Thanks to Joe Terwilliger (Columbia and Oxford) for straightening out my confusion about lots of LINKAGE things, including the different versions of UNKNOWN.

• UNKNOWN from a User's Perspective
• More details on UNKNOWN Specifications
• Versions of UNKNOWN
• UNKNOWN from an Algorithmicist's Perspective
• Error Detection in UNKNOWN