  \dirtree{%^^A
    .1 [repository]\DTcomment{the Repository Folder}.
      .2 sdo\DTcomment{the folder with our SDO files}.
        .3 omg\DTcomment{files for OMG 'stuff'}.
          .4 corba-idl.tex\DTcomment{The CORBA IDL language}.
          .4 omg-mda.tex\DTcomment{The OMG Model-driven Architecture}.
          .4 [...].
        .3 ieee\DTcomment{files for IEEE 'stuff'}.
          .4 802-1.tex\DTcomment{The IEEE LAN concept}.
          .4 ethernet.tex\DTcomment{The Ethernet protocol}.
          .4 [...].
        .3 ietf\DTcomment{files for IETF 'stuff'}.
          .4 dns.tex\DTcomment{The DNS protocol}.
          .4 uri.tex\DTcomment{The URI specifications}.
          .4 [...].
        .3 [...].
      .2 [...].
  }