PRD 1 is inconistent about the use of blank lines.

1. Some sections, e.g 2, 2.1.1, 3.1. 3.2 , 3.2.1 start with a blank line after the header, but others. e.g. 2.1 don't . I think it should be consistent (personally I would leave them all out).

2. Many, but not all, sections end with a blank line. I don't mind this as much but again I think it should be consistent

3. Some sections, mainly in chapter 5, end with multiple blank lines, which I think is entirely gratuitous, e.g. 1543/4, 1625/7, 1667/9