The Apply button causes the selected context object to be applied
    to any DECset tools displaying on the same DECwindows display as
    is the Context window. You may also double-click on the context
    in the Context Database Entries field to apply the context. In
    addition to applying this context, any command line qualifiers
    that are in effect are then re-applied to the tool.

    A named context must be saved before a context apply operation is
    initiated.