strip.xysplom(which.given, which.panel, var.name, factor.levels,
 shingle.intervals, par.strip.text = trellis.par.get("add.text"),
 strip.names = c(TRUE, TRUE), style = 1, ...)strip.default.strip.default.c("corr","beta","corr.beta").  If it finds them, it goes up the
  calling sequence to locate the data for the panel.  Then it calculates
  the correlation and/of regression coefficient and inserts the
  calculated value(s) as the value for the strip label.xysplom