A.6 Formal System Identifier Definition Requirements (FSIDR)

A.6.7.1 Local storage manager notation form

The notation form local storage manager (localsm) is used for storage managers that are local to a particular system. An SOS of a local storage manager will normally need to be converted when an FSI in which it occurs (and the storage object it identifies) is moved to another system. For some SMs and operating systems, the needed conversion could be purely syntactic, or even non-existent, if the originating system's directory structure is replicated on the receiving system.

                    <!-- Local storage manager -->
<!notation
   localsm        -- Local storage manager --
                  -- Clause: A.6.7.1 --

   PUBLIC "ISO/IEC 10744:1997//NOTATION FSISM
           Local Storage Manager//EN"

-- Attributes: smcommon --
>

A.6.7.2 Starter set local storage managers

The starter set local storage managers are:

osfile

The SOI is an absolute or relative file identifier (that is, possibly including drive, path, filename, extension, etc.) in a form recognized by the local operating system's file open function.

osfd

The SOI is a number. The storage object specification locates the storage object that is created when the operating system reads from the file descriptor with that number. For example, in Unix and DOS systems, fd:0 will read the storage object from standard input.

The content of an osfile SOS (that is, the SOI) conforms to the rules of the local operating system. Where those rules allow an SOI to be relative (e.g. an operating system's relative filename), it normally is interpreted relative to the current storage object when the specified and current storage managers are the same.

                   <!-- Local Storage Managers -->
             <!-- PART OF A NON-MANDATORY STARTER SET -->
<!notation
   osfile         -- Operating system file --
                  -- Clause: A.6.7.2 --

   PUBLIC "ISO/IEC 10744:1997//NOTATION FSISM LOCAL
           Operating System File//EN"

-- Attributes: osfile, smcommon --
>
<!attlist #NOTATION
   osfile         -- Operating system file --
                  -- Clause: A.6.7.2 --

   FSIBase  NAME     #FIXED localsm
>

<!notation
   osfd           -- Operating system file desciptor --
                  -- Clause: A.6.7.2 --

   PUBLIC "ISO/IEC 10744:1997//NOTATION FSISM LOCAL
           Operating System File Descriptor//EN"

-- Attributes: osfd, smcommon --
>
<!attlist #NOTATION
   osfd           -- Operating system file desciptor --
                  -- Clause: A.6.7.2 --

   FSIBase  NAME     #FIXED localsm
>

A.6.7.3 Portable storage manager notation form

The notation form portable storage manager (portblsm) is used for storage managers whose SOSs are recognized on many (but not necessarily all) operating systems. A portable SOS will normally not need to be converted when an FSI containing it is moved to another system.

                  <!-- Portable Storage Manager -->
<!notation
   portblsm       -- Portable storage manager --
                  -- Clause: A.6.7.3 --

   PUBLIC "ISO/IEC 10744:1997//NOTATION FSISM
           Portable Storage Manager//EN"

-- Attributes: smcommon --
>

A.6.7.4 Global storage manager notation form

The notation form global storage manager (globalsm) is used for storage managers whose SOSs never need to be converted because they are independent of any real storage environment.

                   <!-- Global Storage Manager -->
<!notation
   globalsm       -- Global storage manager --
                  -- Clause: A.6.7.5 --

   PUBLIC "ISO/IEC 10744:1997//NOTATION FSISM
           Global Storage Manager//EN"

-- Attributes: smcommon --
>

A.6.7.5 Global storage managers

The starter set global storage managers are:

literal

The SOI is treated as the literal text of a storage object.

NOTE 522 Literal text is used chiefly as a connector when concatenating other storage objects. Numeric character references can be used to insert record boundaries between the concatenated objects.

ThisOne

The SOI must be empty. The storage object is normally the current storage object. However, if the attribute this entity (entity) is specified, the "storage object" is the sequence of characters of the entity named in the attribute value, or the current entity if the attribute value is empty.

NOTE 523 ThisOne can be used to make system identifiers portable. In the following example, the entity "ent1" occupies the last 500 octets of the current storage object. If the storage location of that object were changed, it would not be necessary to change the ent1 entity declaration.

<!ENTITY ent1 system "<ThisOne extents='-500 -1'>">

                   <!-- Global Storage Managers -->
            <!-- PART OF A NON-MANDATORY STARTER SET. -->
<!notation
   literal        -- Literal storage manager --
                  -- Clause: A.6.7.6 --

   PUBLIC "ISO/IEC 10744:1997//NOTATION FSISM GLOBAL
           Literal Text//EN"

-- Attributes: literal, smcommon --
>
<!attlist #NOTATION
   literal        -- Literal storage manager --
                  -- Clause: A.6.7.6 --

   FSIBase  NAME     #FIXED globalsm
>

<!notation
   ThisOne        -- This storage object storage manager --
                  -- Clause: A.6.7.6 --

   PUBLIC "ISO/IEC 10744:1997//NOTATION FSISM GLOBAL
           This Storage Object//EN"

-- Attributes: ThisOne, smcommon --
>
<!attlist #NOTATION
   ThisOne        -- This storage object storage manager --
                  -- Clause: A.6.7.6 --

   FSIBase  NAME     #FIXED globalsm

   entity         -- Entity whose characters are used --
      CDATA       -- Lextype: ENTITY --
                  -- Constraint: empty string means this entity --
      #IMPLIED    -- Default: the octets of this storage object --
>

A.6.7.6 Container storage manager notation form

The notation form container storage manager (contnrsm) is used for storage managers that contain other entities. Whether a container storage manager SOS needs to be converted depends on whether it contains system-dependent information such as file identifiers, as is the case for TAR. For sbento, on the other hand, the SOIs are relative to the entity and the SM is therefore effectively global.

NOTE 524 The storage of the container entity itself depends on the SMs used for that purpose, and is independent of the universality of the container notation.

To locate an object in a container, it is necessary to specify both the SOS of the container and of the object within it. As the container could itself be stored in a container, several levels of SOS might be required. While storage manager notations could be defined to provide for such situations, formal system identifiers provide a simpler and more flexible approach by using separate entity declarations for the container and the contained objects.