healthcare costs

What is the philosophy behind medicare and HC calculations?

Healthcare is a major retirement cost. I see a couple of brief mentions of part B in the manual, but would like a reasonable explanation of how healthcare costs should be treated using this program. It sounds like an estimate of part B premiums is included (but not sure) in the calculations; but no mention of Part A, C, D, or dental for that matter. Can you provide a briefing on how healthcare costs should be accounted for using this tool?