Comments are treated exactly as footnotes - but only if you have decided in the Start Assistant (or in the Document options) that you want to translate them. If you do not want to translate them, they are simply ignored.
If you translate the comments, you have to treat them in the same way as you treat footnotes (see Footnotes and Endnotes).
To manually take them over into the translation box please use the command: Take over comment. (In the case of comments no special reference is added to the source segment.)
Note: When you copy a source segment which includes comments through the command Copy source text the comments are NOT copied. When a TU with comments is saved in a translation memory the comments are NOT included.