https://github.com/yahoo/locator#example-defining-your-own-semantics

it is mostly describing where are located each type of resources, and based on that, plugins can infer some configs. in the case of yui modules, `app.yui.plugin()` could use that info to include or not the module into the server group, client group or both.

as for this particular case, do you want me to remove it? since we are sure we are not trying to `use` those 4 modules on the server side, we should be ok.