Each column is read downwards. For example, the designation "Wall" applies to all colors downwards.
So, numbers 2842, 2843, and 2838 are a complete exterior color scheme for wall, trim, and accent, respectively.
Picture too small? Click on the picture to enlarge. For purposes of ordering the product from Sherwin-Williams, each code is preceded by "SW." So, 2834 would be "SW-2834."