File title

A file title is a description of the file, which may be used for any purpose. It may contain almost any chars with some exceptions. The file's name may be generated from its title.
Example: This is a file title! :)

Filename or file name

A filename is a string uniquely identifying a file among its siblings. There are strict rules for its syntax. It's the file's address, so it's not part of the file itself. Changing a file's name won't change its file hash. The domain of a branch is considered to be the root file's name. Filenames usually match URL path segments.
Example: this-is-a-filename

Reserved filenames

Reserved filenames are system filenames white-listed for specific uses. For example, the filename .Request is reserved for request method files.

System filenames

System filenames are filenames starting with a dot followed by an uppercase letter, for example .Request. System filenames can only be used if they are among the reserved filenames.