In a few words...
NDF is a data description language designed by Eugen Systems to describe the data used in the game.
Its main asset is the ease it provides to describe a set of coupled data.
What does it look like ?
// Creation of an object named "MyObject" of class "TTruc" MyObject is TTruc : ValueString = 'Hello World' // Creation of an object named "YourObject" YourObject is TTruc : AutreTruc = MyObject ValueInteger = 322
Remark
The example above use the indented syntax, it can also be written using the parenthesis syntax, as follow.
Warning: If you don't know Python, you are probably unaware of this indented syntax. It uses the indentation (whitespace) to indicate the run of a block. More info about it here:
// Creation of an object named "MyObject" of class "TTruc" MyObject is TTruc ( ValueString = 'Hello World' ) // Creation of an object named "YourObject" YourObject is TTruc ( AutreTruc = MyObject ValueInteger = 322 )