When your source document contains the sentence:
Dr. Jekyll faces horrible consequences when he lets his dark side run wild with a potion that changes him into the animalistic Mr. Hyde.
without any SRX rule active, CafeTran will *segmentate this into three segments:
Dr.
And:
Jekyll faces horrible consequences when he lets his dark side run wild with a potion that changes him into the animalistic Mr.
And:
Hyde.
This is because CafeTran always segments after a full stop '.', followed by an uppercase Letter.
You should, of course, use an SRX file to prevent such splitting. But in case you didn't, you can use the Join segments button under the target segment box: or use the keyboard shortcut Alt+Up.