CNSTR(6)                                                 CNSTR(6)

          cnstr - Plan B volume constraints and attributes

          The Plan B bns(4) program permits the application to mount
          at a given mount point those volumes whose names and
          attributes match the ones given as arguments, as said in

          Volume attributes can be used as constraints to determine
          which ones of the volumes available for a given mount point
          are of interest for the application. A constraint is a set
          of values for attributes that refer to properties of the
          resource volume. Both volume announces and volume mount
          requests carry a constraint used to pair them.

          A constraint is a single argument, field, or string. Its
          format is a set of attr=value pairs delimited by white
          space. No space may be around the equal sign. Also, when
          using rc(1), it is important to quote all the
          attribute/value pairs together, or they would become differ-
          ent constraints, and not a single one.

          By convention, the following attribute names and values are
          used through the system, This convention should be followed
          or users will not know how to request a given property for a
          resource. Of course, this is highly regional and the version
          shown here corresponds to customs at URJC.

               Attribute Name      Values    Description
               Type      type                Type for the resource
                                             serviced.  Usually corre-
                                             sponds to the data format
                                             for the device involved.
                                   text      text without null charac-
                                   bin       program binary
                                   dir       file hiearchy
                                   pcm       audio PCM data.
                                   mp3       MPEG 2 layer 3 data.
               Arch      arch                Architecture for the
                                             resource. Commonly used
                                             for bin types.
                                   386       Plan B (or Plan 9), 386.
                                   arm       Plan B (or Plan 9), ARM.
                                   lin       Linux on 386 PC.
                                   win       Windows on 386 PC.
                                   sym       Symbian, native.
               UI        gui                 User interface service.

     CNSTR(6)                                                 CNSTR(6)

                                             Identifies the type of
                                             device available.
                                   big       Large graphics device
                                   small     Small graphics device
                                   txt       Text only device
               location  loc                 Name used to represent
                                             the location of the vol-
                                             ume. Corresponds to a
                                             directory in /where that
                                             keeps context for the
                                             given location.
               user      user                Identifier used for the
                                             user, to identify volumes
                                             of interest for (or owned
                                             by) a particular user.
               machine   sys                 Identifier used for the
                                             machine, to identify vol-
                                             umes served by that par-
                                             ticular machine.
               domain    dom                 Identifier used for the
                                             adminstrative domain, to
                                             locate volumes within
               Con       net                 Connection. Specifies the
                                             quality of the link used
                                             to reach the volume.
                                   ok        Latency seems to be ok.
                                   bad       Latency is a bad one.

          Other types and values not documented here may exist,
          although those commonly used should be described above. The
          convention is that attributes not listed here are not stan-
          dard at URJC.

          planb(1), namespace.planb(4), bns(8), mount(2).