Repositories play a pivotal role in an integrated reuse- based application development environment. Reusing software components implies their persistent storage and maintenance, and the ability to efficiently find them. Repositories built with reuse in mind can be considered as special-purpose information systems, required to support powerful semantic modelling, flexible retrieval of varied software descriptions of multimedia nature, and efficiency optimization directed towards a large variety of classes rather than large populations per class. The Software Information Base (SIB), described in this paper, is an illustrative case where issues of organisation, multi-paradigm access and challenging implementation choices are set forth. Keyword Codes: D.2.2; D.2.9; H.3.3