A PML Core Specification Version 1.0 has been published as an Auto-ID Center Recommendation. The specification documents the core part of the Physical Markup Language (PML Core), explaining details the scope of PML Core and its relation to the Physical Markup Language. The document provides usage scenarios, articulates the requirements, explains design decisions, and supplies XML schemas and sample instance documents. The goal of PML is to "provide a collection of common, standardized vocabularies to represent and distribute information related to EPC Network enabled objects."

The EPC Network is "an enabling technology that will transform the global supply chain through a new, open global standard for real-time, automatic identification of items in the supply chain of any company; the EPC Network was developed by the Auto-ID Center, a global research team directed through MIT and affiliated labs around the world, supported by more than 100 leading companies." Examples of EPC objects include observations by sensors such as RFID readers, "configuration files for infrastructure components such as RFID readers or e-commerce documents featuring EPC data such as advanced shipping notices containing EPCs of the items shipped. Although these different vocabularies might have diverse contents, they will be using naming and design rules common to the PML."

The PML vocabularies "provide the XML definitions of the data exchanged between components in the EPC Network system. XML messages interchanged in the systems should be instantiated from these PML schemas. The PML development is part of the Auto-ID Center's effort to develop standardized interfaces and protocols for the communication with and within the Auto-ID infrastructure. PML does not attempt to replace existing vocabularies for business transactions or any other XML application libraries, but complements these by defining a new library containing definitions about EPC Network system related data."

Bibliographic Information

PML Core Specification 1.0. Auto-ID Center Recommendation for the Physical Markup Language. By Christian Floerkemeier (Auto-ID Center Lab Switzerland), Dipan Anarkat (Uniform Code Council), Ted Osinski (Uniform Code Council), and Mark Harrison (Auto-ID Center Lab UK). 15-September-2003. 48 pages. Section 6 (Appendix, pages 39-43) provides XML schemas for 'PmlCore.xsd' and 'Identifier.xsd'. Available from the Auto-ID Center. "This document has been reviewed by Auto-ID Center Members and other interested parties and has been endorsed by the Director of Auto-ID Center. It is a stable document and may be used as reference material or cited as a normative reference from another document. Comments on this document should be sent to the Auto-ID Software Action Group mailing list."

EPC System Network Overview

"Radio Frequency Identification is a technology used to identify, track and locate assets. The vision that drives the developments at the Auto-ID Center is the universal unique identification of individual items. The unique number, called EPC (electronic product code) will be encoded in an inexpensive Radio Frequency Identification (RFID) tag. The EPC Network will also capture and make available (via Internet and for authorized requests) other information that pertains to a given item to authorized requestors..."

"Readers are devices responsible for detecting when tags enter their read range. They may also be capable of interrogating other sensors coupled to tags or embedded within tags. The Auto-ID Reader Protocol Specification 1.0 defines a standard protocol by which Readers communicate with Savants and other hosts. The Savant also has an 'adapter' provision to interface to older readers that do not implement the Auto-ID Reader Protocol..."

"Savant is middleware software designed to process the streams of tag or sensor data (event data) coming from of one or more reader devices. Savant performs filtering, aggregation, and counting of tag data, reducing the volume of data prior to sending to Enterprise Applications. The Auto-ID Savant Specification 1.0 defines the working of Savant, and the interface to Enterprise Applications..."

The EPC Information Service makes EPC Network related data available in PML format to requesting services. Data available through the EPC Information Service may include tag read data collected from Savant (for example, to assist with object tracking and tracing at serial number granularity); instance-level data such as date of manufacture, expiry date, and so on; and object class-level data such as product catalog information. In responding to requests, the EPC Information Service draws upon a variety of data sources that exist within an enterprise, translating that data into PML format. When the EPC data is distributed across the supply chain, an industry may create an EPC Access Registry that will act as a repository for EPC Information Service interface descriptions. The Auto-ID EPC Information Service Specification 1.0 defines the protocol for accessing the EPC Information Service..."

"The Object Name Service provides a global lookup service to translate an EPC into one or more Internet Uniform Reference Locators (URLs) where further information on the object may be found. These URLs often identify an EPC Information Service, though ONS may also be used to associate EPCs with web sites and other Internet resources relevant to an object. ONS provides both static and dynamic services. Static ONS typically provides URLs for information maintained by an object's manufacturer. Dynamic ONS services record a sequence of custodians as an object moves through a supply chain. ONS is built using the same technology as DNS, the Domain Name Service of the Internet..." [adapted from the spec]

Physical Markup Language (PML) Overview

"PML provides a collection of vocabularies to represent information related to EPC Network enabled objects. The PML CORE is a vocabulary used to represent data captured by the EPC Network. The SAVANT Extension is a vocabulary for standardization of the communication between the Savant and enterprise applications..."

If the processing capabilities of the components allow for an XML based information interchange, the PML Core vocabulary should provide the payload mark-up of sensor data communication between: (1) A Savant/EPC Information Service and an external application; (2) Savants attached to individual sensors and Savants that aggregate information; (3) A sensor (such as an RFID reader) and a Savant... It is supposed to be used as the format for any interchange of the captured data with and within the Auto-ID infrastructure, while being agnostic about how the data are stored or transported..."

"The purpose of the core part of the physical markup language (PML Core) is to provide a standardized format for the exchange of the data captured by the sensors in an Auto-ID infrastructure, e.g., RFID readers. PML Core provides a set of schemas that define the interchange format for the transmission of the data values captured. These data entities might be accessed directly from the sensor, or from data routers and data stores such as the Savant or the EPC Information Service that distribute the captured data..."

PML Core focuses on observables -- physical properties and entities that are capable of being observed or measured by a sensor -- rather than the observational and performance characteristics of the individual sensors or the interpretation of the observed values. Any possible interpretation of these raw data is handled by other vocabularies under the PML umbrella. PML Core is [thus] one of the vocabularies in the collection of vocabularies under the PML umbrella..."

The PML developers believe that "by focusing on what is unique to Auto-ID [they] can provide a vocabulary that suits the needs of the Auto-ID community and at the same time avoids reinventing the wheel by defining a new vocabulary for elements that are already defined in existing business standards such as UBL, EAN.UCC, RosettaNet and many more. PML Core thus focuses on providing a flexible framework to represent data captured by sensors in the EPC Network..."

"Messages based on the PML Core schema can be exchanged between any two XML enabled systems in the EPC Network. Typically the information exchange based on the PML Core schema will occur between Savant and the EPC Information Service and/or other enterprise applications. This does not preclude other opportunities for usage of the PML Core schema. Any other industry vertical or organization with requirements that match the PML Core model may make use of it by importing the schema into their specific XML schema or application. Tool support based on the PML schema may be another such opportunity. In general we can say that PML Core messaging can be accomplished between any 2 systems capable of XML messaging..." [adapted from the spec]

About the Electronic Product Code (EPC) Network

EPCglobal is leading the development of industry-driven standards for the revolutionary Electronic Product Code (EPC) Network to support the use of radio frequency identification (RFID) in today's fast-moving, information rich trading networks. We are a member-driven organization entrusted by industry to create global standards that offer the promise of more efficient supply chains and higher-quality information flow around your key trading partner relationships.

EPCglobal works with its End User and technology provider community to standardize all aspects of the EPC Network, including: The EPC Numbering System; RFID Tags, Readers, and Interface Protocols; Savant, for Real-Time Event Management; Object Naming Service (ONS); Physical Markup Language (PML); EPC Information Services; and EPC Network Reference Architecture.."

EPCglobal is a joint venture between EAN International and the Uniform Code Council (UCC). We are a not-for-profit organisation entrusted by industry to establish and support the EPC Network as the global standard for immediate, automatic, and accurate identification of any item in the supply chain of any company, in any industry, anywhere in the world. Our objective is to drive global adoption of the EPC Network. The EPC Network was developed by the Auto-ID Center, an academic research project headquartered at the Massachusetts Institute of Technology (M.I.T.) with labs at five leading research universities around the globe. [from the FAQ]