We have some people who want to use xrefs inside content that is conditionalized out, either inside topics that have been conditionalized out at the map level, using ishconditions, or (more commonly) topics that have ishconditions applied to elements that contain xrefs.
My take on it is "don't do that," both from a DITA standpoint, and from the standpoint of what works. However, I would be interested in hearing some best practices or guidance for this kind of use case that I could pass on.