Full Idea
It is normal to classify free logics into three sorts; positive free logics (some propositions with empty terms are true), negative free logics (they are false), and neuter free logics (they lack truth-value), though I find this unhelpful and superficial.
Gist of Idea
Same say there are positive, negative and neuter free logics
Source
Stephen Read (Thinking About Logic [1995], Ch.5)
Book Reference
Read,Stephen: 'Thinking About Logic' [OUP 1995], p.133