This image comes from the Hebrew National website and depicts the front of the cow as kosher and the back as non-kosher (link). The truth is that this is a fairly strict interpretation of halakhah.
R. Dr. Ari Zivotofsky writes about this in his regular column in Jewish Action (67:1, Fall 2006, p. 58):
Misconception: Nikkur achoraim (rendering the hindquarters of an animal fit for kosher consumption) is a Sephardic practice that is banned by rabbinic fiat for Ashkenazim and thus not performed in the United States.R. Zivotofsky proceeds to document communities where the hindquarters were eaten and where not. After much historical discussion, he describes the current situation (p. 61):
Fact: There is no such ban, and nikkur was practiced in many Ashkenazic communities into the twentieth century. The practice of some communities to refrain from eating hindquarters, owing to the difficulty in excising the forbidden sections, continues to exist among both Ashkenazim and Sephardim.
Today, nikkur of the hindquarters is practiced in Israel, and is supervised by many of the Sephardic badatzes as well as the Rabbanut. In addition, the OU supervises nikkur of deer hindquarters in the United States, because in deer, only the gid hanasheh and blood require removal, but not the chailev.