Heat Pump Defrost Question

https://www.mediafire.com/file/vb9g5zytt5azzih/pdf-40299-37737.pdf/file

Heat Pump Defrost Question Is it normal for a heat pump to blow steam from the outdoor unit in winter? Ours did that during the freeze last February and I panicked a bit. Sounds like it might just be the defrost cycle from what I'm reading here