'm not guessing , all the names can be read in 3dpatch.vol by opening it with WordPad , and I've extracted all the stock artwork from 3dpatch.vol , 3dfall.vol , and 3dwinter.vol Upon my 3rd review (geeeze) of the set I've had working for months and examining the .vol files and the files I've extracted from them ....... 'coast0x' us not amoung the names. 'coast' , 'coast0' and 'coast00' are valid names , all are the larger "close" detail size bitmaps. 'coast' is the all water tile used adjacent to the the other coast tiles with land on them.'coast00' is the all water tile used beyond 'coast' in the ocean. I don't think 'coast0' is used .. and I'm seeing all custom ocean and coast without it. All 'x' tiles are 1/2 the size of their same named conterparts and are used at distance to reduce texture loads with so many tiles in view. 'coastx' is only 1/2 sized all water tile for the Spring , and displays for both 'coast' and 'coast00' at distance. Certainly can't hurt to have 'coast0' in there tho .. Fly In short: 256^2 coast = land + water 256^2 coast00 = all-water tile adjacent too land + water = coast 128^2 coastx = long distance replacement for coast and coast00