  A Topic Map is a structured network of hyperlinks that points into an
information pool. Topic Maps have an existence independent of the information
pool and hence different Topic Maps can form different layers above the same
information pool and provide us with different views of it. We explore the use
of Topic Maps with the Unified Column Descriptor (UCD) scheme developed in the
frame of the ESO-CDS data mining project. UCD, with its multi-tier hierarchical
structure, categorizes parameters reported in tables and catalogs. By using
Topic Maps we show how columns from different catalogs with similar but not
identical descriptions could be combined. A direct application for the Virtual
Observatory community is that of merging catalogs in order to generate
customized views of data.
