E910_performance workbench callstack parse

hi, can somebody clarify what does it mean by this piece of info captured in callstack.txt

    1. ENTER: GetEnvironmentValue

    1. EXIT: for GetEnvironmentValue=2   0 seconds 

does it mean the called BSN has triggered some error , something like missing setup...

1. ENTER: GetDefaultBranch

        2. ENTER: GetAuditInfo

        2. EXIT: for GetAuditInfo=0   0 seconds 

    1. EXIT: for GetDefaultBranch=0   0 seconds 

how about this one with 0 returned  ?

TQ