GS1 EPC Tag Data Standard 1.6 - Indicod-Ecr

734735736737738739740741742743744745746747748749750751752753754755756757758759760761762763764765766767768769770771772773774775urn:epc:id:sgtin:0614141.112345.400Each EPC scheme provides a namespace of identifiers that can be used to identifyphysical objects of a particular type. Collectively, the EPC URIs from all schemes areunique identifiers for any type of physical object.6.1 Use of the EPC URIThe EPC URI is the preferred way within an information system to denote a specificphysical object.The structure of the EPC URI guarantees worldwide uniqueness of the EPC across alltypes of physical objects and applications. In order to preserve worldwide uniqueness,each EPC URI must be used in its entirety when a unique identifier is called for, and notbroken into constituent parts nor the urn:epc:id: prefix abbreviated or dropped.When asking the question “do these two data structures refer to the same physicalobject?”, where each data structure uses an EPC URI to refer to a physical object, thequestion may be answered simply by comparing the full EPC URI strings as specified in[RFC3986], Section 6.2. In most cases, the “simple string comparison” method sufficies,though if a URI contains percent-encoding triplets the hexadecimal digits may requirecase normalization as described in [RFC3986], Section 6.2.2.1. The construction of theEPC URI guarantees uniqueness across all categories of objects, provided that the URI isused in its entirety.In other situations, applications may wish to exploit the internal structure of an EPC URIfor purposes of filtering, selection, or distribution. For example, an application may wishto query a database for all records pertaining to instances of a specific product identifiedby a GTIN. This amounts to querying for all EPCs whose GS1 Company Prefix and itemreference components match a given value, disregarding the serial number component.Another example is found in the Object Name Service (ONS) [ONS1.0.1], which uses thefirst component of an EPC to delegate a query to a “local ONS” operated by an individualcompany. This allows the ONS system to scale in a way that would be quite difficult ifall ONS records were stored in a flat database maintained by a single organization.While the internal structure of the EPC may be exploited for filtering, selection, anddistribution as illustrated above, it is essential that the EPC URI be used in its entiretywhen used as a unique identifier.6.2 Assignment of EPCs to Physical ObjectsThe act of allocating a new EPC and associating it with a specific physical object iscalled “commissioning.” It is the responsibility of applications and business processesthat commission EPCs to ensure that the same EPC is never assigned to two differentphysical objects; that is, to ensure that commissioned EPCs are unique. Typically,commissioning applications will make use of databases that record which EPCs havealready been commissioned and which are still available. For example, in an applicationthat commissions SGTINs by assigning serial numbers sequentially, such a databasemight record the last serial number used for each base GTIN.Because visibility data and other business data that refers to EPCs may continue to existlong after a physical object ceases to exist, an EPC is ideally never reused to refer to aCopyright ©2005- 2011 GS1 AISBL, All Rights Reserved. Page 28 of 218