An S,S- and R,R-lactide stream suitable for polymerization is prepared by producing a low molecular weight poly, depolymerizing the low molecular weight poly to form a mixture of S,S-, R,R- and meso-lactide, and separating meso-lactide from this mixture to form an S,S- and R,R-lactide stream. In one embodiment of the invention, a metal interconnect and a barrier layer are formed into an interlayer dielectric and the metal interconnect and the barrier layer are planarized to the top of the ILD. The wireless-specific switches and the individual connections therebetween form a parallel, tree-like PNNI node structure in relation to the rest of the ATM network, so that the wireless-specific switches belong, in addition to said PNNI node structure, also to the node structure of the regular ATM network. Then, the scanning probe is positioned at a second point located on the magnetic track to mark the second point as a second radial position index.