The external repository stores information specified in function prototypes, program definitions, class definitions and interface definitions.
The information stored about these source units must consist of all information required for activation and checking conformance. This information includes
This information about a source unit, excluding the externalized name of the source unit, is called its signature.
If a REPOSITORY directive is specified with the ON phrase, the compiler puts this information into the external repository as it compiles each compilation unit.
If a REPOSITORY directive is specified with the CHECKING phrase, either explicitly or by default, the compiler issues a warning when these characteristics of definitions and prototypes do not exactly match the information, if any, in the external repository for the associated definition.
The details on the association of the name of a source unit with information in the external repository are specified in the section The Repository Paragraph in the chapter Environment Division.