To add to BinaryCats' info.
There's a little-known feature called Key Dopesheet (hotkey: CTRL + SHIFT + L) which adds a key to all existing dopesheet items, including attachments. I like to think of it as keying a pose.
If you use that, you can then copy that whole column, and can paste it elsewhere.
It's great for when you have to copy a pose to another animation, or have your character hold a pose for a short time, then continue moving.
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You can filter what dopesheet items you add to by selecting specific slots or bones.
You can find more handy shortcut keys here: http://esotericsoftware.com/spine-cheat-sheet
