ABNF pattern question - maybe for Joseph?

literal                 = literal-value / literal-ref
literal-value           = literal-context "/!/" data-xref
literal-ref             = literal-context "/!/()"                                                              <== NEW

context                 = peer / peer-relative-context / relative-context
peer                    = 1*xref
peer-relative-context   = peer relative-context
relative-context        = 1*( singleton / ( collection [ member ] ) )

collection-context      = [ peer ] *( singleton / ( collection [ member ] ) ) collection

member-context          = member [ relative-context ]

literal-context         = [ peer ] *( singleton / ( collection [ member ] ) ) ( attribute-singleton / collection attribute-member )