The Version/Revision Conundrum

You have a PLM system. Fundamental to this system is the concept of a version and a revision. However, this is probably the most misunderstood process in the PLM realm. Also these terms mean a wide variety of things to different people and are often used interchangeably and without consistency.

For the purposes of the rest of this piece, we will use the following definitions:

Version – represents a small incremental change in the design that would be saved in the database. Versions are not necessarily saved permanently beyond a revision.

Revision – represents a significant event in the design process and is saved permanently in the database for reference throughout the design process.

Diagrammatically, the difference is illustrated below:

Version Revision

It is often confusing to talk to about this subject because the terms are used interchangeably. Also, the distinction between a version and a revision is not clearly understood, even to the extent that participants think that they are the same thing. Because of this, it is important that any organization with a PLM system ensure that all the participants clearly understand the definition and what the difference is.

In a collaborative PLM environment, participants are very dependent on viewing or using data generated by other participants. For example, a headlamp engineer needs the position of locating holes in the sheetmetal to be able to design his locating pins (if this is the order of precedence). In this scenario, the headlamp engineer will say “I need the latest sheetmetal to begin my design.” This statement is common in design and engineering teams. However, it is inherently imprecise because it begs the question: Do you need the latest version or latest revision?

Based on the definition given earlier, what is really required is the latest revision. A version is a work in progress and could be incomplete or half-done because the responsible author may be in the middle of a redesign or new concept. For this reason, a version should not be visible to the larger organization; only revisions should be accessible, as they satisfy the definition of “best so far.” This concept is very difficult to get across to a lot of people and represents the conundrum referred to in the title. It takes some courage to work on data that will change sometime in the future, but this is absolutely required in an efficient design process.

The version/revision conundrum also leads to some interesting human psychology. Consider any collaborative design environment where multiple participants have to submit data into a PLM system to progress a large project. It is important in these environments that all participants follow the mantra of “publish early, publish often” or, per the nomenclature of this piece, create many revisions. This is based on the principle that incomplete or slightly inaccurate data is better than no data at all.

However, process managers often put in systems that highlight inaccuracies or incomplete data, effectively punishing early publishers. So data authors hold back and only create revisions when they are certain of accuracy, late in the process. This is counterproductive.

So pay attention to the version/revision conundrum; clear definitions and policies of this simple issue can greatly improve a PLM process.


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