If you go to the MKVToolnix Web page, you will find that these tools comprise three programs: mkvmerge, mkvinfo, and mkvexctract. However, the Fedora Core 6 mkvtoolnix package does not provide mkvinfo. That is a bug. The reason I am reporting this here is that <http://bugzilla.redhat.com/bugzilla> is specified as the packager of mkvtoolnix in the package info. The bugzilla Web page that I am entering this bug report with asks one to specify the "component", but mkvtoolnix is not included in the list of components. The Web page does not allow you to leave the component field blank, or specify "other". I hope this will not lead to confusion.
mkvinfo is present in the mkvtoolnix-gui package.