The Ramp block is a virtual subsystem with other blocks underneath, which should have indices 0:3 through 0:9.
If you right-click that block and select Mask -> Look Under Mask, you'll see that.
Off-topic: It looks like you have floating annotations for the labels "y" and "z". Did you mean to have those attached to the signal lines? It can be a bit tricky to get the positioning right, but if you double-click a signal line you can name it directly and the label will snap to the line.
- Sebastian
