As you are undoubtedly aware, legal English differs from “ordinary” English in numerous respects. Words and phrases which mean one thing in normal English usage can mean something entirely different in a legal context. One such example is the word assignment. In everyday English, the term assignment normally means a “task” or a “job”, i.e. the teacher gave the student an assignment. However, in legal English, the term assignment is most often used to mean a complete transfer of rights (unlike a license, which in effect is a partial transfer of rights). Whereas a licensor grants rights to a licensee while maintaining ultimate ownership, an assignor grants all of the rights owned to the assignee.
The dueling definitions of assignment can rear its ugly head when translating a contract into English from another language. Many countries style agreements such that a party is given an assignment (i.e. a task) from another party. This is often reflected in the opening clause of an agreement:
"Party A was given an assignment by Party B to construct buildings on the premises."
However, in legal English, the term assignment is rarely used in this manner, partly to avoid confusion with the “other” assignment (i.e. a complete transfer) and partly because “giving” an assignment usually connotes unequal bargaining power, market power or status (teachers give assignments to students; bosses give assignments to employees; but generally one company would not give an assignment to another). For these reasons, when drafting such clauses in English, it is best to avoid using the term assignment altogether. It is more common to phrase such clauses as follows:
"Party B was requested by Party A to construct buildings on the premises."
or (even better)
"Party B undertakes to construct buildings on the premises."