The bottom layer. It owns Dialect, Args, SQLer, Raw, Quote and ErrUnsupportedDialect, and it imports only the standard library.
It says nothing about SQL, and that is load-bearing. Operators, join types, sort directions and keywords are SQL vocabulary and belong to the layers above, because a Gremlin or MongoDB target has no JOIN and no <>. TestRender_ServesANonSQLTarget drives this layer with a non-SQL dialect and TestRender_ImportsOnlyStdlib pins the floor. A construct, operator or keyword added here is a defect even when it compiles.
The page for this package is docs/render/README.md, with runnable snippets — every one of them copied from a test whose expected output go test checks. The documentation index is ../docs/README.md and the repository README is ../README.md.