VNX Monitoring and Reporting: What Does The Gray Graph Line in VNX M&R Reports Represent?

In the VNX M&R "Block Throughput (IOPS)" there is a gray graph line in the report.  What does that line represent?

Also, out of the eight SP (service processor) metrics listed in the graphs legend, only five SP metrics display on the graph.  Those remaining three SP metrics are grayed out in the legend of the graph (below the image of the graph).  Please see the example below:

The graph only shows the top five contributors out of all of the systems listed for "Block Throughput (IOPS)."  Only five graph lines can be displayed in the graph (six if one includes the gray out graph line). 
 
The gray chart line represents the sum of all other items in the legend below the graph (anything more than the top 5 contributors), all of the additional SP throughputs that are grayed out.
 
The grayed out throughput metrics are being used, but they just aren t the top five contributors.  The values from grayed out boxes (which are just not the high performers) are totaled together and are shown as the gray graph line.