inaccessible due to its protection level

What are you trying to do exactly? Why are you trying to access this internal object?

If you are trying to select data from a view, your code should look like that:

foreach(ComputingLines line in DetailsView.Select())
{
    //Do something with the line.
}

P.S. this was posted to the Field Service forum -- to increase the odds somebody will see this and respond, please post to the Customization forum in the future.