You can force all hyperlinks to open in a single window by selecting 'Shared Window/Tab' from the 'Open link in' drop down list.

This is useful if you are hyperlinking product codes for example that when clicked opens up a window/tab with more information. Instead of a new window or tab opening every time, links with this property will open in the same window or tab. 

Note that whether a window or tab opens is determined by the browser.