A single register holding risks, assumptions, issues and dependencies, and usually decisions, with the type recorded on every line.
RAID stands for risks, assumptions, issues and dependencies, and most working versions add decisions as a fifth type. Keeping them in one place is a filing decision rather than a methodological one, and a sensible one: the escalation path stays visible when the issue sits a few rows below the risk it came from. What the single artefact must not do is merge the fields, because likelihood is meaningful for a risk and meaningless for an issue, and a column of certainties makes the whole register unsortable. Keep the type on every line and let the irrelevant cells stay empty.
See also
The list of events that could affect the work but have not yet, each scored for likelihood and impact, with an owner and a planned response.
The list of events that have already occurred and are affecting the work, each with an owner and a resolution date. Likelihood no longer applies.
Where this comes up
One bar per variable, the widest at the top, all of them measured against a baseline down the middle. A tornado diagram ranks what could move an outcome, and by how much.
A risk might happen. An issue already has. That single difference decides which artefact a line belongs in, what you record about it, and who you have to tell.
Contingency reserve sits inside the cost baseline, for risks already named and priced. Management reserve sits above it, for the ones nobody named. Level and authority, not size.
Most risk registers record one number per row. The number that actually justifies spending money is the distance between two of them.