OK, thanks.
I think the whole "natural language as rules" thing is a red herring - or rather, that it's about purely aesthetic preferences for how rules are stated, rather than anything about how rules are actually adjudicated or applied.
For instance, here are the 4e rules on cover (Rules Compendium, p 219; underlines added):
Targets behind a low wall, around a corner, or behind a tree enjoy some amount of cover. They can’t be hit as easily as normal - the attacker takes a penalty to attack rolls against them. There are two degrees of cover.
*Partial Cover (–2 Penalty to Attack Rolls): An attacker takes a –2 penalty to attack rolls against a target that has partial cover (sometimes simply called “cover”). The target is around a corner or protected by terrain. For instance, the target might be in the same square as a small tree, obstructed by a small pillar or a large piece of furniture, or crouching behind a low wall.
*Superior Cover (–5 Penalty to Attack Rolls): An attacker takes a –5 penalty to attack rolls against a target that has superior cover. The target is protected by a significant terrain advantage, such as when fighting from behind a window, a portcullis, a grate, or an arrow slit.
The following rules govern both degrees of cover.
Determining Cover: To determine if a target has cover, choose a corner of a square the attacker occupies, or a corner of the attack’s origin square, and trace imaginary lines from that corner to every corner of any one square that the target occupies. If one or two of those
lines are blocked by an obstacle or an enemy, the target has partial cover. (A line isn’t blocked if it runs along the edge of an obstacle’s or an enemy’s square.) If three or four of those lines are blocked yet line of effect remains - such as when a target is behind an arrow slit - the target has superior cover.
The bits of these rules that I've underlined are all expressed in natural language, and require the table (and, ultimately, the GM) to adjudicate the fiction.
Here are the 5e rules (Basic PDF, p 74):
There are three degrees of cover. If a target is behind multiple sources of cover, only the most protective degree of cover applies; the degrees aren’t added together. For example, if a target is behind a creature that gives half cover and a tree trunk that gives three-quarters cover, the target has three-quarters cover.
A target with half cover has a +2 bonus to AC and Dexterity saving throws. A target has half cover if an obstacle blocks at least half of its body. The obstacle might be a low wall, a large piece of furniture, a narrow tree trunk, or a creature, whether that creature is an enemy or a friend.
A target with three-quarters cover has a +5 bonus to AC and Dexterity saving throws. A target has threequarters cover if about three-quarters of it is covered by an obstacle. The obstacle might be a portcullis, an arrow slit, or a thick tree trunk.
A target with total cover can’t be targeted directly by an attack or a spell, although some spells can reach such a target by including it in an area of effect. A target has total cover if it is completely concealed by an obstacle.
The 5e rules for
total cover are covered, in 4e, by the rules for
line of effect and
blocking terrain, and it's a reasonable criticism of the
organisation of the 4e rules that these things are not all treated together, but rather are spread over pages 107-8, 206 and 219 (albeit with some internal cross-referencing). Otherwise the rules are basically the same, and require the same sort of adjudication (how thick is the tree trunk? how big is the furniture? etc). The 4e rules do elaborate a bit more on how the system of squares feeds into that adjudication, but that's a particular instance of the general 4e use of squares as a tool for positioning and managing effects in combat. It doesn't change the necessary element of GM adjudication.
