From Hutchison Software:
TAC Tool analyses existing text based logs, both system and proprietary. It uses search strings stored in an XML file to quickly analyze log files and provide fast answers to known technical issues. It also takes advantage of log messages that are output by programmers when a problem occurs. An example of a standard log file is the Microsoft Windows event log which contains a lot of information which can be used to solve particular issues. An example of a proprietary log file is the one generated by TAC Tool. With TAC Tool you can build a knowledge base by adding a new search and resolution once you know the issue, so you'll never have to search a log file for that solution again.