The IV link connnects to the main verbs of infinitive clauses. The goal of IV is to make the correspondance between link-grammar and traditional dependency grammars more concrete. IV always makes a cycle with the TO link, which identifies the start of the infinitive phrase.
+------IV-----+ +--TOf-+---I--+ | | | we are going to arrive on time
See also the WV link, for connecting to head-verbs to the left wall, the CV link for connecting to the head-verb of subordinate clauses and the AF link for connecting to adjectival complements. Sometimes, the B link can play a similar role for relative clauses.
See also the CP link, which connects to quotation and paraphrasing verbs, as does Eq link and COq link.Grammar Documentation Page.