My understanding is that there are two different ways to play the rules. In one way—their "new" way—the "crest lines" are actually "hillock lines", and the slope depictions are not slopes in the KGP/Pegasus Bridge sense, although they behave somewhat similarly. Instead they indicate folds in the terrain that add to the cost either when crossing a "hillock line" or on their own.
We know that talking about rules is not always so easy... but lets try to not digress on the interpretations. It is very important that you know Hillock (F6) rules so please read it.
I cannot understand where you read that "crest lines" are "hillock lines" can you indicate me? And also I wrote which is the meaning of the slope depictions, they dont indicate "folds" but "hillocks", where the hillocks are terrain so for F6 chapter "... Units on a non-Summit (6.6) hillock hex are at Level ½ (assuming the
overlay is on Level 0 terrain) ....". The hillocks on each level go from the slopes depictions on a given level hexes (taking in account the level height of the center dot of the hex) to the directly upper crest line, that means that every hex between these two kind of borders are 1/2 level higher then the base of that given level. I dont think it is ambiguous but please indicate me which passage is not understandable
Then obviously if i am on a hillock on map level 2 i will be at 2.5 level and i will treat level 3 as an Hillock (read Hillock Summit F6.6).
In a word the wonderful world of ASL give us rules for 1/2 level terrain and we are using it not on DTO or on level 0 Kursk terrain. Thats it.
In relation to "hillock lines" the folds are oriented two different ways. One orientation is along the same hexside as a "hillock line", e.g. O5/P4. This adds a half-level to the cost of crossing that hexside, and makes it black. The other orientation is "perpendicular" to the "hillock line", e.g. N8/O8 & Q8/R7. These occur in pairs (mostly) and indicate a section of "hillock line" that costs two half-levels to cross. The two orientations can be used in combination, e.g. X6/X7 which is also between the perpendicular pair V7/W8 and Z7/Y8, and costs three half-levels to cross. I am guessing crossing the "new slopes" but not crossing a "hillock line", e.g. P6/P7, also costs a half level. I am also guessing that the "new slopes" don't affect actual levels for height advantage, LOS over obstacles, etc.
No orientation, no perpendicular nor parallel, i never talked about orientation. if in a lower level hex adiacent to a crest line there is an hillock that crest line will be half level high (again please read Hillock Summit F6.6)
and we are giving help to Players depicting this case in RED. If both the adjacent lower level hex and the crest line hex are hiillocks
or both them are not hillocks then the crest line height is one full level and depicted in BLACK. Finally if the hillock is only on the crest line hex
and not in the lower level adjacent hex the crest line height will be 1.5 levels (depicted for help in BLUE). The last two cases for LOS rules may create Blind Hexes, not the half-level crest lines (but we know that out of LOS hexes are created by the Hillocks in other ways, please read again F6 chapter)
Hillock rules F6 together with A6 and B10 give us all we need in terms of movement costs, LOS and relation with obstacles (we used also rules from BFP "European hillocks" regarding half level hindrances)
Thats all, nothing more complex than this, you must only apply the rules, as always