In RSF, a ''container'' is a [component|PrimitiveComponents] of type [UIContainer|https://saffron.caret.cam.ac.uk/svn/projects/RSFUtil/trunk/src/uk/org/ponder/rsf/components/UIContainer.java]. UIContainer simply has the function of containing other components, in a "free-form" way (as opposed to hardwired component "clusters" such as [UISelect]). UIContainer can't be used usefully except as a base class - e.g. [UIForm] and [UICommand] are derived from UIContainer, via the concrete intermediary [UISimpleContainer|https://saffron.caret.cam.ac.uk/svn/projects/RSFUtil/trunk/src/uk/org/ponder/rsf/components/UISimpleContainer.java]. The "other" line of descent from UIContainer which avoids UISimpleContainer contains only [UIBranchContainer]. Note that these classes unlike components from other frameworks are all very small, and specify virtually no behaviour. The "container" hierarchy is probably the most untypical in RSF in that it does actually contain some methods, but just to abstract the functions of locating and iterating over child components.

See the dedicated page on [primitive components|PrimitiveComponents] for more details.