Article I: On Interpretation Properly So Called

167. DEFINITION. Interpretation, strictly taken, is a clearer exposition of those words which are obscure or ambiguous.

DIVISION. Interpretation of law is distinguished in many ways:

1. By reason of object, one is declaratory, or comprehensive, which declares obscure words of the law; another is extensive, which extends the law to similar cases; another finally is restrictive, which confines the law to certain designated cases, although it seems general, for example if a prince declares that the word clerics extends to tonsured men alone, but not to those who have ascended to higher orders.

Comprehensive interpretation is named purely such. It is in the law from the beginning: for example, if the discourse is about sons, even illegitimate sons are comprehended under this word. Extensive interpretation is called not purely such, because the sense is not clearly imbibed in the law, for example, that under the name of father, even grandfather, under the name of dead, even civilly dead, ought to be understood.

2. By reason of cause, one is authentic, another usual, another doctrinal, concerning which one must treat especially.