DG connects the word "the" with proper nouns. In general, proper nouns may not take determiners; but we do allow proper nouns to take the determiner "the". This allows things like
The Emir of Kuwait died. The Supreme Soviet met today.but not
*I have known many Kuwaits. *We need a Soviet.Other uses of determiners with proper nouns are allowed with cost 2; see "D: Determiners with Proper Nouns".
DG is used in the construction "The X-er, the Y-er." See "ER". It is also used in certain idiomatic time expressions like "I left the moment I saw him"; see "TT".
Grammar Documentation Page.