COMPASS Medium and Long Term Plans

A first indication of the COMPASS future plans with possible time lines was provided to the CERN/SPC on June 12, 2008 and a proposal to CERN/SPSC is being prepared. This Letter of Intent outlines the physics issues and the status of preparation. A request is formulated for SPS muon beam delivery in the medium term for precision measurements on the transverse and longitudinal spin structure of the nucleon. The proposals to study the Generalised Parton Distribution functions via measurements of the Deeply Virtual Compton Scattering and to study the Transverse Momentum Dependent distributions via measurements of the Drell-Yan process are outlined.