Figure 2: The master function for HTSC, , provides a least upper bound for bulk layered superconductors, and is believed to be accurate to 10 K. This function is based on the zigzag percolative model for self-organized HTSC dopant networks [28, 30]. The original figure [30] has been modified to include the most recent data [34] on BCCOF; the acronyms are as in [30]. Covalent network glasses [20] are centered on = 2.4, but the stabilizing effect of the rigid planes shifts the cuprate center to = 2.