1. A method for evaluating representative labels representing data elements within a semi-structured data source, said method comprising: generating a respective representative label for each of a set of identified instances of a data element within a semi-structured data source; generating a generalized representative label that matches each of the representative labels generated for the identified instances; and evaluating a resilience of the generalized representative label to structural changes of the semi-structured data source by estimating, for a set of possible structural changes to the semi-structured data source, a probability of the generalized representative label satisfying a set of resilience criteria.