The final product (final skin css file) is a contacted file, so it doesn't need a -min.css extension because there is no "non compressed" version of that file since it's concated and minimized at build time.
The core file is added to the build so implementors that don't want our skin can include that as the base for the component and write their own skin on top of it. Eventually, when there are more than one skins, the base css file will be the base for all skin variants. Then skin specific file will only contain that skins specific rules.
As for "compressed CSS" files that are for non-skinnable components (cssgrids, cssreset) these are actual modules in the system, they can be "used" in a `YUI().use()` statement so they follow our normal module guidelines.
The core file is added to the build so implementors that don't want our skin can include that as the base for the component and write their own skin on top of it. Eventually, when there are more than one skins, the base css file will be the base for all skin variants. Then skin specific file will only contain that skins specific rules.
As for "compressed CSS" files that are for non-skinnable components (cssgrids, cssreset) these are actual modules in the system, they can be "used" in a `YUI().use()` statement so they follow our normal module guidelines.