There's open, and then .....
Open Source doesn't just mean that you can read the Source Code (and therefore take Freedoms 1 and 3 forcibly, as Freedoms 0 and 2 can be taken forcibly even when the Source Code is withheld). It means that you are *explicitly* granted all four Freedoms.
* Freedom 0: The freedom to run the program for any purpose.
* Freedom 1: The freedom to study how the program works, and change it to make it do what you wish.
* Freedom 2: The freedom to redistribute copies so you can help your neighbour.
* Freedom 3: The freedom to improve the program, and release your improvements (and modified versions in general) to the public, so that the whole community benefits.
The old PINE licence curtailed Freedom 3 by restricting the distribution of modified versions; therefore, it did not meet the accreditation requirements to be called Open Source. This is in spite of the availability of the Source Code.