$maybe summary' <- summary

#{summary'}

#{content} $maybe (((_, modifyView), modifyEnctype), modifyTranss, ((_, addTransView), addTransEnctype)) <- forms

_{MsgSystemMessageEdit}
^{modifyView}

_{MsgSystemMessageAddTranslation} ^{addTransView} $if not (null modifyTranss)

_{MsgSystemMessageEditTranslations} $forall ((_, transView), transEnctype) <- modifyTranss ^{transView}