Inflections go the other way around.In classic mode, given a missing constant Rails underscores its name and performs a file lookup. On the other hand, zeitwerk mode checks first the file system, and camelizes file names to know the constant those files are expected to define.While in common names these operations match, if acronyms or custom inflection rules are configured, they may not. For example, by default "HTMLParser".underscore is "html_parser", and "html_parser".camelize is "HtmlParser".