"Model Time" significance when running modelers

Kindly help me to get the details of the below queries :

(1)  What does "Model time" mean ? 

        1>  Is it  the time when device modelling was initiated or

        2>  When device was modelled successfully without any errors or warnings.

(2) Does the ‘Model time’ shown on Device overview page is the reflection of modelling time when:

      1> User runs modeler(s) manually

            or

      2> Device models automatically after predefined interval of 12 hours using collector configuration property(Modeler Cycle Interval (mins))? 

(3) Does Zenoss keep record of whether device modelling completed successfully or failed ?