There is no such thing. It simply means the general features that most of the Mahayana schools have.
This really is a tough one, and I am inclined to agree with Astus.
But I wonder, if we had to propose a template for standard Mahayana, how would we do that (perhaps it requires another thread).
I used the term Mahayana Paramitayana because I think that generally all Mahayana Schools would uphold the the Paramitas/Perfection of generosity, ethics, patience, effort, concentration and wisdom.
I would also propose that all the Mahayana schools (as well as Theravada for that matter) uphold the 4 Dharma Seals:
All that is conditioned is impermanent,
All that is tainted is suffering,
Nirvana is peace,
All phenomena are empty and devoid of self.
Also, there is the idea of Bodhicitta, the mind or spirit of enlightenment, wishing to become a Buddha for the benefit of all sentient beings. The methods to achieve that aim, however, are widely variable as well as the philosophies behind those methods. The vastness of the Mahayana corpus makes this discussion a very difficult one because, as Astus mentioned, certain practice traditions within Mahayana emphasize different Sutras and Shastras.
In order to ensure my mind never comes under the power of the self-cherishing attitude,
I must obtain control over my own mind.
Therefore, amongst all empowerments, the empowerment that gives me control over my mind is the best,
and I have received the most profound empowerment with this teaching.
brtsal ba'i bkhra drin