Electro-hydraulic actuator

I need to control an electro hydraulic actuator from a PIC. I've some experience with doing this, but the actuator schematic has me a bit confused. The data sheet indicates that you swap the + and - leads to change direction. An h bridge should work, but the data sheet shows doing it with a SPDT switch/relay. I've attached the data sheet, can someone clue me in here?
Thanks

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