FD & other Mods may or may not agree, But I very much doubt that a categorical set of written rules is possible &/or enforceable, in the real world of these forums.

For a starter, there are different circumstances regarding -
1) The severity of incidents, which may well range from quite minor, to absolutely abhorrent!

2) The frequency of incidents, which could range from the only time a particular member has strayed, to harassing a member at almost every post, to just harassing everyone, every post!

Then there are inherent differences between those making the judgements (the Mods), those who have made the post which is perhaps seen to be affecting others & those who feel they may be being targeted?

As far as Mods are concerned, I doubt any past or present Mod could rightly claim to have been perfect with all of their decisions & non decisions.
That said, Mods are not qualified judges & nor are we paid huge sums, to ensure we spend 24/7 sitting in front of a computer. In fact, Mods are not paid at all, we are generally just trying to assist, so the forum can operate at a reasonable level & members don't go off the rails, too much.

But, that does happen, from time to time people do go off the rails and hopefully between the Forum owner & the mods, we will generally rectify most situations or certainly try to, either by taking some action/s or by providing some advice.   

Whilst this will not answer all possible circumstances that may arise, it may provide some assistance to those wondering why some things happen & why somethings don't and for that reason I will re post this in a permanent sticky.