It is often convenient to name files and folders with a date and time, such as standard ISO 8601 format: 2014-12-10T22:35:28.460Z.

Unfortunately, the Mac’s HFS+ file system uses the COLON as a path separator just as Unix-like OSes use SOLIDUS / (slash) and Microsoft OSes use REVERSE SOLIDUS \ (backslash). All three characters must be avoided when naming a file or folder for compatibility.

What character might be commonly used as a replacement for the COLON?

• Using a HYPHEN - makes it tricky to programmatically reverse the conversion to standard format.
• Similarly, the using FULL STOP . (period) makse reverse conversion difficult as they will be misinterpreted as fractional seconds.

For example, when programming in Java 8 on OS X Mountain Lion, calling File::mkdir() for string 2014-12-11T21:33:08 results in a folder named 2014-12-11T21/33/08.