Vault - History
 

Can you explain how Visual build assighns a value to the needtobuild macro when it checks history? I am trying to re write that part to apply the yes or no to a global macro that can be used between instances of visual build.

If you're referring to the 'Check (Vault)' step in the ContinuousIntegration.bld sample, see the vbld_StepDone script event for that step (step properties -> Script Editor button).
http://www.visualbuild.com/Manual/contintegsample.htm