Editing .plists with defaults

Shell Programming and Scripting
1

I've done simple edits with defaults, but they usually are the parent parameter. For example changing the value of "DateCellWidthCache" =.

What if I want to change a parameter in one of the sub categories such as "MMM d, y' '",? How do I type that out at the end of my defaults write command?:

defaults write com.apple.program xxx

DateCellWidthCache =     {
        DateCellCacheVersion = "B Version";
        DateCellFormats =         (
            "MMMM d, y' '",
            "MMM d, y' '",
            "M/d/yy' '",
            "MMMM d, y",
            "MMM d, y",
            "M/d/yy",
            "Yesterday ",
            "Today ",
            Yesterday,
            Today
        );

I am not trying to edit this .plist, this is just for example purpose.

2

For change FontSize in DateCellWidthCache i'm using :

defaults write com.apple.mail DateCellWidthCache -dict-add FontSize 11

hope it will help you.