The 2nd item in each pair is the string to display in the entry. A command of '-' indicates a separator line. The display string is ignored in this case, but has to be present nevertheless. A command name has to be unique over all menubuttons added to a menubar. Accessor method allowing the reconfiguration of all entries in the menubar.
Access is given based upon the symbolic name of the entry.
The mapping to the menu widget of the entry and its index in that is done here.