Reserved characters in Sync
|.||Period or full stop/full point'|
Use of "." (period character) in a file name can cause an application (i.e. like Sync) to unexpectedly recognize a file with an unsupported file type suffix. For example, a file named "example_filename.txt" might be correctly recognized as a text file. But a file named "example.filename.txt" could result in an unsupported file type error (if the application does not support a file type of ".filename" (such as Sync)).