The development files are the include files needed to compile C programs, the PKG-CONFIG .pc files and the static libraries.
|-- include | `-- libgda-5.0 | [... except the libgdaui/ directory ...] `-- lib |-- libgda-5.0 |-- libgda-5.0.a |-- libgda-5.0.la |-- libgda-report-5.0.a |-- libgda-report-5.0.la |-- libgda-xslt-5.0.a |-- libgda-xslt-5.0.la `-- pkgconfig |-- libgda-5.0.pc |-- libgda-report-5.0.pc `-- libgda-xslt-5.0.pc