"transfer a series of values between applications that apply different types to those values and applications that don't" If we thought about it as an API mech

"transfer a series of values between applications that apply different types to those values and applications that don't" If we thought about it as an API mechanism, we would parse the strings and apply rules to sanitise or reject it. Here is a principle for thinking about data. Distinguish internal data structures (persistence, search) from interchange structures (APIs). Codebase A should not be able to directly access the structures of Codebase B. To communicate, they must use explicit APIs. At the moment, this principle is not mainstream. The CSV loader is not sure if it is loading an interchange format or persistence format. Another, that happens regularly: (1) developer builds a database as a storage mechanism. (2) developer decides to have other separate codebases query into that database. Is the database an application-data-structure (interal) or an API (external)? It is acting as both.