One of the research areas of the NIST Web Metrics Testbed is how to record the behavior of users as they attempt to perform given tasks during interaction with a Web-based application. The captured log data can be valuable for analyzing and improving the usability of such applications. This log data is quite complex and therefore a common file format is needed to allow various software components (such as recorders, parsers, analyzers, and visualizers) to exchange information. The goal then is to establish a Framework for Logging Usability Data - hence: "FLUD". NIST Special Publication 500-248 provides a full explanation of the design and rationale for FLUD.

The parser accepts a logfile formatted as defined in the FLUD specification. It can generate three kinds of output: a parse file, a pretty-print HTML file, and a set of userpath files for VisVIP. A logfile represents the activity of one subject during a single test session.

Here is an example of a raw logfile and its pretty-printed representation.

See NIST Web Metrics disclaimer.