Tes5Mod:Mod File Format/REGN

REGN are "regions", but not in the locational sense (those are LCTN). Each region ties together ambient information (weather/music/etc), presumably so they can be dropped into settings and provide a complete ambience.

Between the thick line are repeatable field sets, RPLI/RPLD come in pairs, and every occurrence of the bottom fields is preceded by an RDAT (sole exception: RDM0/RDSA can be under same RDAT). RDAT can also appear by itself (though rare).

C	V	Field	Name	Type/Size	Info
+		EDID	Editor ID	zstring
+		RCLR	region color	rgb	Map Color (unknown where used)
-		WNAM	world name	formid	World (WRLD).
-		RPLI		uint32	Edge Fall-off (World Units)
-		RPLD	data for "pl"?	struct[]	series of 8-byte structs, vary in length from 32 to 172 look like floats, coords?
-		RDAT	data header?	struct	8-byte struct uint32 - flags? common values <10 ubyte[4]? - sample values 01-37-00-00, 00-32-00-00
-		RDMO	music	formid	Music (MUSC) formid. Can appear with RDSA under same RDAT or on its own.
-		RDSA	sound data	struct[]	12-byte struct, total count arbitrary formid - Sound Reference (SNDR) uint32 - Flags 0x01 - Pleasant 0x02 - Cloudy 0x04 - Rainy 0x08 - Snowy float - Chance
-		RDWT	weather data	struct[]	12-byte struct, total count arbitrary formid - Weather (WTHR) uint32 - percent chance (all should add up to 100) formid - Global (GLOB, not used)
-		RDOT	unknown	-	always 0 length
-		ICON	shader?	zstring	path to .dds Trees\CanopyShadow.dds
-		RDMP	Region Name?	lstring	Map Name