Citation Issues

When adding an explanatory note, where is it placed? Usually it seems to go at the end of the citation. (See the middle citation in EE p. 87.) But it seems some comments deserve to appear in the middle of the citation.

For example, when a volume is not paginated, the notice of such is given in place of the page number. (See EE. p. 316.)

Or for file items the arrangement of the records seems to be described right where a page number would appear. (See EE. pp. 421, 423.)

What do you think?

I have a question. I am looking at the citations to vital records in EE.

Some have the vital event date in parentheses. See, for example, pp. 311, 313, and 315. The dates (1890), (1854), and (1727) are enclosed in parentheses.

Others do not have the vital event date in parentheses. See pp. 436-7 where dates 1871 and 1861, and 1895 are not in parentheses.

When are parentheses used? What is the principle involved?