If no value has been defined via a preference or otherwise inherited or manually set, the following are the value of 'no value' for each attribute data type.
- Boolean:
false - Date:
never - Number:
0 - String & String-type:
""(an empty string, no data)
All the other data types are essentially special forms of a String-based data type:
- Action
- Color
- File
- Font
- List
- Set
- URL