See Expression Elements for a full list.
Expression Value: Box padding _boxPad#
Expression Element: Built-in properties
Box padding
The spacing around the Box Text.
Expression Syntax: _boxPad#
_boxPad# will return the padding value of the Box Text shown above:
To change the Box padding right-click on the row and select Properties...
The Properties of BoxText dialog will be displayed to allow you to change the Box padding value.