iframe link target

I have a calendar in an iframe, some of the links (such as a link to the
next month) need to target the iframe, and some links need to target the
mother page.

This confuses me. Should I specify the _parent and _self? What if there
is no parent, what happens with a target = _parent (ie using the same
code outside an iframe)?

And what about seamless? CanIUse is silent on this, how far reaches the
support?
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pentapus