It is often convenient to name files and folders with a date and time, such as standard [ISO 8601][1] format: `2014-12-10T22:35:28.460Z`.

Unfortunately, the Mac’s [HFS+ file system][2] 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`.


  [1]: https://en.wikipedia.org/wiki/ISO_8601
  [2]: https://en.wikipedia.org/wiki/HFS_Plus