This disclosure includes a system for aligning an unmounted head gimbal assembly comprising a platform for a base plate of the HGA. A shaft for anchoring in a vertebra or bone section is connected to a receiving part which serves to connect to a rod having a pre-determined diameter. At least one selective erasing sub-field is used to turn off the discharge cells selected in the address interval. The first chip select pad is configured to transfer a first chip select signal. A multisolver matrix that represents the collective effect of movements of each edge segment in the mask layout is used to simultaneously determine the correction amount for each edge segment in the mask layout. Most preferably, the BCF yarns are formed of nylon-6 and exhibit an alpha-crystalline content of less than about 45%, and usually between about 45% to about 55%.