Questions about Challenge difficulty in MAX1 through Extreme

Please let me know if any of the following is incorrect:

- On MAX1, difficulty never existed and was never selectable.

- On arcade MAX2, difficulty was only playable in particular courses in Nonstop/Oni mode.
- On home MAX2, these course-only songs could be unlocked for regular play.

- On a non-fully-unlocked arcade Extreme, difficulty was only playable in particular courses in Nonstop/Oni mode. (Is this true? For example, it would make Legend Road the only way to play PSMO before the game was fully unlocked. What about the -only songs from MAX2? Are they freely selectable?)
- On a fully-unlocked arcade Extreme, and Extreme JP CS, difficulty can be freely selected like any other difficulty.

- On every arcade mix since then, difficulty can be freely selected unless the song is exclusive to Extra Stages.

Those MAX2 only songs are playable by default in EXTREME, AFAIK.

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So on a non-fully-unlocked Extreme, is not selectable except for those MAX2 special songs, in which case it is the only difficulty selectable?

On Max 2, Kakumei was the only song playable on One More Extra Stage.

And some regular songs with difficulty, like BUTTERFLY, LET'S GET DOWN, DYNAMITE RAVE, etc.

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So on a non-fully-unlocked Extreme, a song like BUTTERFLY has selectable, but a song like PSM (unlocked on Final Stage) has selectable but not ?

The use of the symbol is making this really confusing :{

In DDRMAX 2, "" is a mode, not a difficulty level. You play songs back to back, and some of them are unique remixes, which are only playable in this mode. They only have one chart.

In DDR Extreme, is the fifth difficulty level. Previously, there were songs that had charts harder than their maniac charts, but this concept never had an official name (In Dancing Stage it was called "Super Maniac", but in the canon series, new charts just replaced the existing Maniac charts, which were demoted to Edit Edit. Most people referred to the newer, harder charts as "S-Maniac".

In Extreme, some songs have a chart, denoting that they are charts designed specifically for play in the mode. They aren't necessarily easier or harder than the charts, and you can select them at will. Some of the charts unlock after the charts unlock.

From that point on, just denotes a difficulty level higher than .

It's still a difficulty technically, KAKUMEI was the first song to feature all levels, though of course only for ENCORE EXTRA STAGE purposes.

from MAX2-EXTREME basically was meant exclusively for Oni mode, where the challenge is to combo songs on x1, so the charts are generally designed with that in mind. From SuperNOVA on, it's the difficulty harder than , except when X also made it the difficulty level of shock arrows, which can be much easier than or harder. But the UI will let you know what charts those are.

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Let's ignore Kakumei, because I can't really explain that, other than the fact that they were torn between creating a chart that truly reflected the song, and a chart that could realistically be full combo'd at 3x speed by players at the time. I don't think the OMES chart is playable anywhere but the OMES? The course that unlocks at the same time as the song just has you play the (harder) chart selectable in mode.

In MAX2, the idea wasn't "Songs can have 5 difficulty levels now. The new level is called ". That was a concept that only came into it's own in Extreme, to get around the problem that Kakumei had one chart too many to display on the song select screen, and you had all these other songs which only had one chart.