OneDbf:AddRelation(cKey,cAlias,nOrder): public: return true
  One relation definition is appended to this database.

  Parameter description:
  ~~~~~~~~~~~~~~~~~~~~~~
  cKey: character: no default
   The key expression in a form of text string, when connecting the databases
   the SEEK command after this evaluated expression is performed.

  cAlias: character: no default
   The alias workarea for seek command.

  nOrder: numeric: no default
   The active  index file order in cAlias workarea.