Why do device names skip from disk0s2 to disk0s4? Where are disk0s1 and disk0s3?

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Usually a standard dual-boot Mac will have the following partition scheme: disk0s1 – EFI, disk0s2 – OS X HFS partition, disk0s3 – Apple Boot Recovery partition, disk0s4 – Boot Camp partition. By default Boot Runner will display the OS X partition and the Boot Camp partition. The EFI partition is not bootable so it doesn’t make sense to add it to the Boot Runner.