As meta-data become of ever more importance to the Web, we will need to start managing such meta-data. We argue that there is a strong need for meta-data validation and aggregation. We introduce the WebMaster Approach for verifying semi-structured information and show how it can be used to validate, aggregate and visualize the Meta-Data of an existing Information System. We conclude that the possibility to verify and aggregate meta-data is an added value with respect to content based access to information. 1 Motivation: Meta-Data on the Web The information society demands large-scale availability of data and information. With the advent of the World Wide Web huge amounts of information is available in principle, however size and the inherent heterogeneity of the Web makes it difficult to find and access useful information. A suitable information source must be located which contains the data needed for a given task. Once the information source has been found, access to the data therei...