I'm trying to understand what does this mark mean " " in IF function (Logical
test). This has been done in many Excell worksheets but I could not find the
author to ask him. If any one can understand the meaning from the examples
below, please let me know or provide any helpfull material.

=IF(B8-$D$40.05,B8-$D$4,IF(A8="","",0))
=IF(E8="","",IF(ABS(D8-E8)0.05,0,D8-E8))

Thanks