Day One stores your journal in a file with
.dayone file extension. This file is something known as a file package. A file package is file that appears to be a single file but is actually a folder. In Finder you can right click on these files and select “Show Package Contents” to see the contents of the folder.
Inside of the journal file are subfolders containing your journal data. Inside of the
entriesfolder is a file for each of your entries. Each entry is named with a UUID and has the extension of
.doentry. These files contain the basic entry data such as text, creation date, location, etc. The entry file format is an XML Property List.
photos folder contains the photos for your entries. Each photo has the same name as its corresponding entry but with a
.jpg file extension. These files are compressed and have a maximum resolution of 2100px x 2100px.
When your journal file is moved to iCloud things change slightly. Instead of
Journal.dayone it is renamed to a folder called
Journal_dayone. This is because iCloud does not work well with file packages. In every other respect
Journal_dayone is exactly the same as a