In this section, we describe algorithm CtoS, which generates an edit script between two trees, given an edge cover of their induced graph. Before we can describe this algorithm, we need to understand the relationship between an edit scripts between two trees and edge covers of their induced graph. Therefore, we first define the edge cover induced by an edit script. That is, we describe how, given an edit script between two trees, we generate an edge cover of the induced graph. (Note that this process is the reverse of the process the algorithm CtoS performs. However, a definition of this reverse process is needed for the description of the algorithm.)