204 The goal of many FOSS4G deployments, and indeed development efforts, are the creation of Spatial Data Infrastructures. SDIs are intended to be hierarchical - with activity devolved down to the lowest level, and the "whole being greater than the sum of the parts". In practive this is largely unrealised, and the tools are not yet good enough to achieve it. This paper examines the fundamental requirements for SDIs to interoperate, and focusses on the emerging methodologies for creating data standards so that SDI components are worth connecting. Implemented examples using the Geoserver platform will be provided, and an introduction will be provided to activities developing data standards support within Geoserver and Geotools. Finally, a series of guidelines and ideas for turning the "OpenSDI software stack" into a genuine SDI toolkit will be explored, in advance of detailed requirements analysis to be expected from an emerging alignment of global SDI architectures. FOSS4G2006 - Free And Open Source Software for Geoinformatics Session 10 : SDI-OGC Robert Atkinson rob@socialchange.net.au Robert Atkinson rob@socialchange.net.au <MaKaC.conference.ContributionType object at 0xb4936b6c>