DC isolation and rms value of isolation

This is regarding isolation of an dc-dc converter. What is the correlation between isolation voltage in dc and isolation voltage in rms. Is there any way with which dc isolation can be calculated if the rms value is provided and vice versa?
Thanks.

The problem is the relation of different test voltage specifications and rated voltage.

A manufacturer application note discussing some numbers:

As an additional remark, for long term reliable AC isolation, partial discharges must be safely avoided.

thanks a lot