History

The Physical Markup Language not only describes the current state of the physical world, but previous states of the physical world. In other words, PML records history - both changes to physical objects and their environments.

Rather than assuming only some elements within PML change with time, we assume all elements may change, although with greater or lesser frequency.

Therefore we introduce a timestamp element that is an optional component of every other component within the language.

We include in this version of the Physical Markup Language a simple data structure to reference these protocol and to provide high level interpretation of the incoming data streams.

Timestamp

We introduce a ts (timestamp) element to record events. The ts element includes a mandatory type attribute that indicates the nature of the timestamp. The type attribute may assume the following values: "begin" for the beginning of an on-going state, "end" for the end of a particular state and "span" for a time interval. If the type attribue is not set, the time is assumed to be for a discrete event - a point in time.

Depending on the type , timestamp may contain one or two date elements. If the type attribute is not set, the timestamp is assume to record a discrete event and, therefore a single date element is required. Similarly, if type is set to "begin" and "end" types one date element is needed. However, if type is set to "span" requires two data elements are required.

<ts type=["begin", "end"]>
<date> . . . </date>
. . .
</ts>
 
<ts type=["span"]>
<date> . . . </date>
. . .
</ts>

 

Usage

Because we assume every element in the Physical Markup Language may change, the timestamp element is allowed very broad application.

Specifically, the ts (timestamp) element may be included in any element of the Physical Markup Language and the ts element may contain any element in PML.

In this way the timestamp element may associate an element or a group of elements with a specific point in time or a duration of time.

The timestamp element allows users to specify not only where an object is , but where an object was . The timestamp specification may trace the path of a product, case or shipment as it moves through the supply chain.

 

Specification: Timestamp

 

<ts type=["begin", "end"]>
<date> . . . </date>
. . .
</ts>
 
<ts type=["span"]>
<date> . . . </date>
. . .
</ts>