How to skip some targets ?

[Ramasubbu, Hari]

   How do i skip a target depending on a property being set.
  for example 

 <target1>

 <target2> -This target must be skipped if a property "skip.target2" =true.

 <target3>


Sincerely
Hari Ramasubbu
Technology & System Integration
Verizon