Three marks of Existence question

[wukong]

Greetings all

How are the three marks of existence expressed and taught in the gelug system? i know that they are included in the 'four seals/tenets' but is that the only way in which gelugpas encounter the three marks? are the three marks a sutra teaching or purely pali abhidhamma teaching?

any thoughts?

many thanks in advance

wukong