the value/canonicity of officially published material can vary though. see: those novelizations of movies that add or change bits which weren't part of the script, or manga anthologies drawn by fanartists and printed by the same publishers who release official print works. or even the 50 billionty filler anime episodes for adaptations of shounen-genre manga that often don't have much of any input from the original creator and might be disproved by the source material.