Right-to-Left Mark

The right-to-left mark (RLM) is a non-printing character used in the computerized typesetting of bi-directional text containing mixed left-to-right scripts (such as English and Russian) and right-to-left scripts (such as Arabic, Persian and Hebrew). It is used to change the way adjacent characters are grouped with respect to text direction. (Wikipedia)

This video illustrates how to utilize the RTL and the LTR toolbar buttons in Wordfast Pro.