When using eFP Browser what is the cut-off (numeric) value for the low expression level for absolute and relative values?

Question

[WUSCHEL]

When I am checking out the expression values on eFP Browser during different developmental stages, in different tissues, under different growth conditions, etc. how do I decide certain expression level is low or high.

What numeric value should I use to distinguish between low and high expression level for:

a. absolute values

b. relative values