Biocompatible compositions comprising polyanionic polysaccharides combined with hydrophobic bioabsorbable polymers as well as methods for making and using the compositions are described. In a medium that recordsplays back data including video data and control information, the control information includes information for accessing a specific portion of the video data. The sufficient measurement time is determined by an overlap of measurement gaps and positioning subframes in the second signal. The counterweight unit is positioned adjustably on the arcuate rail. An opening is located in each of the base members which extends through the base members.