MCFM provides W^+ and W^- cross sections separately. In most cases, the 
correlations with W^+ and W^- are very similar, so we just
average the two. If the correlations are different by more than 0.1, we 
provide separate numbers for + and -.
 
So for the correlation between the W and ZZ cross section, for example, the
two numbers correspond to the correlation with the W^+ cross section 
(first #->0.52) and W^- (second #->0..69). For the correlation of VBF(120) 
with W^ +/W^-, the correlations are 0.26 and 0.41.
 
Consider a more complicated case: W correlation with WH (120 GeV). The 4 
correlations are:
 
 W^+/W^+H=0.62
 W^+/W^-H=0.43
 W^-/W^-H=0.68
 W^-/W^+H=0.60
 
We average the first two numbers to give a value for W+ (0.52) and the second 
two numbers to give a value for W^- (0.64), since in the table W^+ and W^- 
are shown explicitly.
 
Consider WH correlation with WbB (300 GeV). The 4 correlations are:
 
 W^+H/W^+bB=0.77
 W^+H/W^-bB=0.60
 W^-H/W^+bB=0.37
 W^-H/W^-bB=0.91
 
We provide two numbers: the first is for W^+H, and is the combination of the 
first two numbers above:[ (0.77+0.60)/2=0.68], while the second is
the combination of the last two numbers [(0.37+0.91)/2=0.64].