RCB stands for the Repertorium van de Belgische Handelscatalogi (Directory of Belgian Trade Catalogues). It is an online aid to trace trade catalogues published in Belgium before c. 1950, in public collections.
Click on a company name to open the corresponding file or search for the name of a city or municipality. You can quickly search using the key combination "Ctrl-F" and go through all search results with the "enter" key.