The site also hosts pointers to other search engines as well as collections of Internet resources on popular subjects. It's just a guess, but I believe OpenText's search engine is really an adveritisment for its commerical document storage and retrieval software. Like a number of the other services, OpenText's interface in entirely menu-driven. It consists of a number of blank fields surrounded by qualifiers. It is obvious from this description that OpenText is strong on phrase searching and the proximity of words.
Field searching is a bit weak.
The document cited above describes regular expressions in terms of the Unix grep command. An understanding of regular expressions will come in handy when using many alternative search tools like Harvest and ListProc mailing list archives. Requiring a Unix computer, the software is written completely in Perl and therefore completely open. Each record can have a unlimited number of fields and field lengths. Consequently it is easy to assign multiple subject heading to Internet resources.