[Luisabens]

However Dzongsar Khyentse Rinpoche (TB) describes four characteristics or "seals of Dharma"

i think it is important to examine the word 'seal' or 'mudra' because i sense the word is used in a different context than the Pali 'lakkhana' (sign, characteristic, mark)

the seals of Dharma refer to the salient characteristics of the Dhamma teachings & realities

where as the originally used the term 'lakkhana' referred to the salient characteristics of the conditioned five aggregates

in general, the term "existence" means "being" or "conditioned arising". it does not mean the unborn Nirvana

for example, when Buddha described the coming into existence of conditioned things, he spoke as follows:

Now what is the cause, what is the origination, what is the birth, what is the coming-into-existence of that fabrication? the three marks of existent or created things, as revealed in the 2nd sermon, were not originally intended to apply to Nirvana, given Nirvana is the 'unborn' or 'uncreated'

regards