An important feature of Doric is the preservance of a lot of archaic peculiarities of Ancient Greek, that is why Doric words and grammar forms are always used for comparative studies of Indo-European languages. Doric language can be traced by official signs and poets' works.
The main features of the Doric language:
a) keeping the archaic long á (e.g. mátér - mother)
b) keeping the archaic Indo-European *w (e.g. newos - young)
c) keeping of the 3rd person verb endings -ti and -nti (e.g. didoti - he gives)
d) the peculiar ending in the 1st person plural of verbs -mes (e.g. didomes - we give, Greek didomen)
e) the definite article toi, tai, and the 2nd person pronoun
tu (thou, Greek su)