Well its possible that it may be the main feature that differentiates if from other FEM programs. However, I would argue that the basic approach of NASTRAN/MYSTRAN is different enough from other FEM programs. For example, NASTRAN is still widely used in the aircraft industry for linear models for a variety of reasons (low on that list is DMAP).
No, MYSTRAN was developed by people that worked on NASA NASTRAN, but is totally independent and designed from the ground up. It has a much more modern code base and is far easier to code/develop/compile. A few attempts have been made to continue the development of the public release of NASA NASTRAN, but there are major roadblocks. AFAIK, there has only been one person to develop it (other than compile it), which is Harry Schaeffer (there is a discussion about his ComLab in the other subforum). Also, due to international restrictions, it can not be released to non-US Citizens. For the most, the community seems to have given up on it, other than still being able to use the version that has been released to the public (since a few people have been able to compile it).
No, MYSTRAN was developed by people that worked on NASA NASTRAN, but is totally independent and designed from the ground up. It has a much more modern code base and is far easier to code/develop/compile. A few attempts have been made to continue the development of the public release of NASA NASTRAN, but there are major roadblocks. AFAIK, there has only been one person to develop it (other than compile it), which is Harry Schaeffer (there is a discussion about his ComLab in the other subforum). Also, due to international restrictions, it can not be released to non-US Citizens. For the most, the community seems to have given up on it, other than still being able to use the version that has been released to the public (since a few people have been able to compile it).