Minecraft wiki entry for Removed_blocks, associated text: In Beta 1.2, colored wool was reimplemented. However, the color scheme was completely different, and coloration was handled via block metadata, rather than defining a new ID for each color. Wool would continue to use metadata (and later block states) to define its color up until the Flattening in 17w47a gave each wool color a unique (albeit non-numeric) block ID again.