rfc2244.txt

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      REFER
           This response code may be returned in a tagged NO response to
           any command that takes a dataset name as a parameter.  It has
           one or more arguments with the syntax of relative URLs.  It
           is a referral, indicating that the command should be retried
           using one of the relative URLs.






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      SASL This response code can occur in the tagged OK response to a
           successful AUTHENTICATE command and includes the optional
           final server response data from the server as specified by
           SASL [SASL].

      TOOMANY
           This response code may be returned in a tagged OK response to
           a SEARCH command which includes the LIMIT modifier.  The
           argument returns the total number of matching entries.

      TOOOLD
           The modtime specified in the DELETEDSINCE command is too old,
           so deletedsince information is no longer available.

      TRANSITION-NEEDED
           This response code occurs on a NO response to an AUTHENTICATE
           command.  It indicates that the user name is valid, but the
           entry in the authentication database needs to be updated in
           order to permit authentication with the specified mechanism.
           This can happen if a user has an entry in a system
           authentication database such as Unix /etc/passwd, but does
           not have credentials suitable for use by the specified
           mechanism.

      TRYLATER
           A command failed due to a temporary server failure.  The
           client MAY continue using local information and try the
           command later.

      TRYFREECONTEXT
           This response code may be returned in a tagged NO response to
           a SEARCH command which includes the MAKECONTEXT modifier.  It
           indicates that a new context may not be created due to the
           server's limit on the number of existing contexts.

      WAYTOOMANY
           This response code may be returned in a tagged NO response to
           a SEARCH command which includes a HARDLIMIT search modifier.
           It indicates that the SEARCH would have returned more entries
           than the HARDLIMIT permitted.

      Additional response codes MUST be registered with IANA according
      to the proceedures in section 7.2.  Client implementations MUST
      tolerate response codes that they do not recognize.







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4.       Namespace Conventions

4.1.     Dataset Namespace

   The dataset namespace is a slash-separated hierarchy.  The first
   component of the dataset namespace is a dataset class.  Dataset
   classes MUST have a vendor prefix (vendor.<vendor/product>) or be
   specified in a standards track or IESG approved experimental RFC.
   See section 7.3 for the registration template.

   The second component of the dataset name is "site", "group", "host",
   or "user" referring to server-wide data, administrative group data,
   per-host data and per-user data respectively.

   For "group", "host", and "user" areas, the third component of the
   path is the group name, the fully qualified host domain name, or the
   user name.  A path of the form "/<dataset-class>/~/" is a convenient
   abbreviation for "/<dataset-class>/user/<current-user>/".

   Dataset names which begin with "/byowner/" are reserved as an
   alternate view of the namespace.  This provides a way to see all the
   dataset classes which a particular owner uses.  For example,
   "/byowner/~/<dataset-class>/" is an alternate name for
   "/<dataset-class>/~/".  Byowner provides a way to view a list of
   dataset classes owned by a given user; this is done using the dataset
   "/byowner/user/<current-user>/" with the NOINHERIT SEARCH modifier.

   The dataset "/" may be used to find all dataset classes visible to
   the current user.  A dataset of the form "/<dataset-class>/user/" may
   be used to find all users which have made a dataset or entry of that
   class visible to the current user.

   The formal syntax for a dataset name is defined by the "dataset-name"
   rule in section 4.3.

4.2.     Attribute Namespace

   Attribute names which do not contain a dot (".") are reserved for
   standardized attributes which have meaning in any dataset.  In order
   to simplify client implementations, the attribute namespace is
   intended to be unique across all datasets.  To achieve this,
   attribute names are prefixed with the dataset class name followed by
   a dot (".").  Attributes which affect management of the dataset are
   prefixed with "dataset.".  In addition, a subtree of the "vendor."
   attribute namespace may be registered with IANA according to the
   rules in section 7.4.  ACAP implementors are encouraged to help
   define interoperable dataset classes specifications rather than using
   the private attribute namespace.



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   Some users or sites may wish to add their own private attributes to
   certain dataset classes.  In order to enable this, the "user.<user-
   name>." and "site." subtrees of the attribute namespace are reserved
   for user-specific and site-specific attributes respectively and will
   not be standardized.  Such attributes are not interoperable so are
   discouraged in favor of defining standard attributes.  A future
   extension is expected to permit discovery of syntax for user or
   site-specific attributes.  Clients wishing to support display of user
   or site-specific attributes should display the value of any non-NIL
   single-valued "user.<user-name>." or "site."  attribute which has
   valid UTF-8 syntax.

   The formal syntax for an attribute name is defined by the
   "attribute-name" rule in the next section.

4.3.     Formal Syntax for Dataset and Attribute Namespace

   The naming conventions for datasets and attributes are defined by the
   following ABNF.   Note that this grammar is not part of the ACAP
   protocol syntax in section 8, as dataset names and attribute names
   are encoded as strings within the ACAP protocol.

   attribute-dacl  = "dataset.acl" *("." name-component)

   attribute-dset  = dataset-std 1*("." name-component)
                     ;; MUST be defined in a dataset class specification

   attribute-name  = attribute-std / attr-site / attr-user / vendor-name

   attribute-std   = "entry" / "subdataset" / "modtime" /
                     "dataset.inherit" / attribute-dacl / attribute-dset

   attr-site       = "site" 1*("." name-component)

   attr-user       = "user." name-component 1*("." name-component)

   byowner         = "/byowner/" owner "/"
                     [dataset-class "/" dataset-sub]

   dataset-class   = dataset-std / vendor-name

   dataset-normal  = "/" [dataset-class "/"
                     (owner-prefix / dataset-tail)]

   dataset-name    = byowner / dataset-normal






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   dataset-std     = name-component
                     ;; MUST be registered with IANA and the spec MUST
                     ;; be published as a standards track or
                     ;; IESG-approved experimental RFC

   dataset-sub     = *(dname-component "/")
                     ;; The rules for this portion of the namespace may
                     ;; be further restricted by the dataset class
                     ;; specification.

   dataset-tail    = owner "/" dataset-sub

   dname-component = 1*UTF8-CHAR
                     ;; MUST NOT begin with "." or contain "/"

   name-component  = 1*UTF8-CHAR
                     ;; MUST NOT contain ".", "/", "%", or "*"

   owner           = "site" / owner-host / owner-group /
                     owner-user / "~"

   owner-group     = "group/" dname-component

   owner-host      = "host/" dname-component

   owner-prefix    = "group/" / "host/" / "user/"

   owner-user      = "user/" dname-component

   vendor-name     = vendor-token *("." name-component)

   vendor-token    = "vendor." name-component
                     ;; MUST be registered with IANA

5.       Dataset Management

   The entry with an empty name ("") in the dataset is used to hold
   management information for the dataset as a whole.

5.1.     Dataset Inheritance

   It is possible for one dataset to inherit data from another.  The
   dataset from which the data is inherited is called the base dataset.
   Data in the base dataset appears in the inheriting dataset, except
   when overridden by a STORE to the inheriting dataset.






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   The base dataset is usually a system-wide or group-wide set of
   defaults.  A system-wide dataset usually has one inheriting dataset
   per user, allowing each user to add to or modify the defaults as
   appropriate.

   An entry which exists in both the inheriting and base dataset
   inherits a modtime equal to the greater of the two modtimes.  An
   attribute in such an entry is inherited from the base dataset if it
   was never modified by a STORE command in the inheriting dataset or if
   DEFAULT was stored to that attribute.  This permits default entries
   to be amended rather than replaced in the inheriting dataset.

   The "subdataset" attribute is not directly inherited.  If the base
   dataset includes a "subdataset" attribute and the inheriting dataset
   does not, then the "subdataset" attribute will inherit a virtual
   value of a list containing a ".".  The subdataset at that node is
   said to be a "virtual" dataset as it is simply a virtual copy of the
   appropriate base dataset with all "subdataset" attributes changed to
   a list containing a ".".  A virtual dataset is not visible if
   NOINHERIT is specified on the SEARCH command.

   Servers MUST support at least two levels of inheritance.  This
   permits a user's dataset such as "/options/user/fred/common" to
   inherit from a group dataset such as "/options/group/dinosaur
   operators/common" which in turn inherits from a server-wide dataset
   such as "/options/site/common".

5.2.     Dataset Attributes

   The following attributes apply to management of the dataset when
   stored in the "" entry of a dataset.  These attributes are not
   inherited.

   dataset.acl
        This holds the default access control list for the dataset.
        This attribute is validated, so an invalid access control list
        in a STORE command will result in a NO response with an INVALID
        response code.

   dataset.acl.<attribute>
        This holds the default access control list for an attribute
        within the dataset.  This attribute is validated, so an invalid
        access control list in a STORE command will result in a NO
        response with an INVALID response code.

   dataset.inherit
        This holds the name of a dataset from which to inherit according
        to the rules in the previous section.  This attribute MAY refer



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        to a non-existent dataset, in which case nothing is inherited.
        This attribute is validated, so illegal dataset syntax or an
        attempt to store a multi-value will result in a NO response with
        an INVALID response code.

5.3.     Dataset Creation

   When a dataset is first created (by storing a "." in the subdataset
   attribute or storing an entry in a previously non-existent dataset),
   the dataset attributes are initialized with the values from the
   parent dataset in the "/byowner/" hierarchy.  In the case of the
   "dataset.inherit" attribute, the appropriate hierarchy component is
   added.  For example, given the following entry (note that \t refers
   to the US-ASCII horizontal tab character):

   entry path        "/byowner/user/joe/"
   dataset.acl       ("joe\txrwia" "fred\txr")
   dataset.inherit   "/byowner/site"

   If a new dataset class "/byowner/user/jo