Error correction in robust data structures is a difficult problem. Several algorithms for correcting structural errors, in certain list and tree structures, are now known. These algorithms have been examined to determine common design features which may prove useful in the design of correction algorithms for other structures. This paper presents a summary of the algorithms studied and the design principles which were derived. The paper is not a "cookbook" for constructing error correction algorithms, but should prove useful to those designing such algorithms. Implications for the design of robust data structures, so that correction may be done easily, are also briefly discussed.