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Basic items: Documents and parts

Revisions

A revision represents a single design iteration or data record of an item.

Somewhat like item numbers, revision sequences define the format and rules by which new revisions are assigned. Unlike item numbers, a specific revision isn't unique to one item; many items can have the same revision value (e.g., "AC" or "15") assigned.

Because multiple part revisions should be able to freely mix in the same inventory bin, best practice dictates that parts don't carry revisions. When we discuss "part revisions", we're really talking about the data revision record that PDXpert uses to distinguish changes to a part's metadata in the database.

A specific item revision has its own release status, with three distinct release states: pending, released and canceled. A pending revision indicates that the current design iteration is not yet approved for use. A released revision indicates that the iteration is available for its intended use. A canceled revision shows that the revision was previously approved for use, but is no longer approved.

You may also see the terms releasing and canceling. These are intermediate states that indicate a revision appears on an implementing change form's Affected item list, but the change form hasn't yet been approved and released.

Revision assignments

PDXpert can assign the next revision value in a sequence, and in fact can switch between revisions formats - say, from numeric to alphabetic - depending on whether the item is in a pre-production phase or a production phase.

The business rules used to control revision assignment comes from (1) the item type's revision sequence(s), and (2) the item's lifecycle phase which defines the item's current relative maturity. Revision sequence formats are defined in the Sequences: Revisions collection.

Item type revision sequences

You can specify one or two revision formats in an item type, and items derived from the type will follow the specification. The initial revision sequence is first used when a new item is created. The subsequent revision sequence may also be specified, which is applied to items after they've reached a production lifecycle phase. If no subsequent revision sequence is specified, the initial revision sequence continues to be used.

Item lifecycle phase's relative maturity

The item lifecycle phase's relative maturity value specifies the application of the item, relative to a production or qualified value of zero. Negative values for relative maturity indicates a pre-production item (such as design, prototype or unqualified), and values greater than zero indicate a post-production maturity (such as service-only, disqualified or obsolete).

First pending revision of an item

As you create the first pending revision of a part record or document, you specify the revision's lifecycle phase:

  • If the lifecycle phase has a negative relative maturity (RM < 0), then the item Type's initial revision sequence determines the particular revision sequence that will be assigned, and its starting revision value is assigned to the first revision string.
  • If the first pending revision's lifecycle phase has a non-negative relative maturity (RM ≥ 0), then the Type's subsequent revision sequence determines the revision sequence, and its starting revision value is assigned to the first revision string. If no subsequent revision sequence has been specified, the item is assigned the initial revision sequence.

Later pending revisions of an item

After you've released the first revision of a part record or document, you can specify the Item Lifecycle Phase for each subsequent revision of the item:

  • If the later pending revision's lifecycle phase has a negative RM, then the immediately-preceding released revision value is incremented using the skip characters of the revision sequence identified in the subsequent revision with RM ≥ 0.
  • If the later pending revision's Item Lifecycle Phase has a non-negative relative maturity (RM ≥ 0) and there's never been a released revision with RM ≥ 0, then the assigned revision is copied from the Starting revision value of the revision sequence identified in the Subsequent revision sequence.
  • If the later pending revision's Item Lifecycle Phase has a non-negative relative maturity (RM ≥ 0), then the immediately-preceding released revision value is incremented using the Skip characters of the revision sequence identified in the Subsequent revision sequence.

The revision is automatically extended using the starting revision value's current leading character type. For example, if the current item revision is "Z" and the leading (left-most) character in the starting revision is "A", then the value will simply be incremented to "AA".

An item's revision format should not reflect its lifecycle phase. An initial revision and subsequent revision can only distinguish between two lifecycle phases, while most businesses have many; some common phases are design, prototype, production, service, obsolete. It's far better to use the revision simply to indicate a change to the item's data, and allow the separate item lifecycle phase to distinguish how the data should be applied. For this reason (and because it's also a lot easier to train for and manage), we recommend that you specify only an initial revision sequence, and leave the subsequent revision sequence empty.

Versions

An item version is an "alias" for a revision. While item revisions typically identify discrete steps in the evolution of an item, versions often are not sequential. Versions are commonly used for computer program files to identify (a) a specific set of features, (b) a set of bug fixes, and/or (c) a particular build number. For example, a version "3.2.203" may indicate the marketing feature set "3.2" plus the compiler build "203". While you have a very good feel for how many releases are represented in going from revision "AA" to "AD", you'd have little idea whether there were a few releases, or several hundred, between versions "1.0.403" and "2.1.1042". In PDXpert, you cannot have a version without also specifying its associated revision.

Structures (parents & children)

In addition to managing items, PDXpert can be used to manage the relationships between items. Item relationships are quite useful for building aggregations of items: they can specify the physical components that go into an assembly or a set of individual chapters that comprise a complete user guide.

A structure lists all of the child items that are used to create the parent. A bill of materials is a particular kind of structure that is used to build a manufactured assembly. Another structure, a data list, contains the individual documents that are required to assemble a more complex document.

An indented structure, or "indented BOM," is a report which shows all of the items that report - however indirectly - to a specific assembly. All items that directly report to the assembly are one level deep; items that directly report to first-level items are two levels deep; and so on. (The top assembly has a depth of zero.) Very complex products can have as many as 10 levels, although shallow structures are much easier and less expensive to manage, particularly in modern continuous-flow production environments.

Most production processes would fail if child items could be added and removed at any time, without careful review and authorization. Just as an item must be formally released on an implementing change, so too must a child item be formally added on or taken off an item structure. The vehicle for formalizing these changes is the Markup list of the item's Structure tab. Once you've added or deleted the appropriate child items, releasing the item revision also implements those markup items. The resulting structure is shown on the Current list of the item's Structure tab.

Displaying child items

Structure tab: Markup list

Prior to an item's release, the Markup list on its Structure tab always shows the most recent released or pending revision for each child item. After release, the Markup tab displays the child revision that was current when the parent was released.

Structure tab: Current list

An item's Current list on its Structure tab will show various child items depending on the parent's release state. When a parent item revision is:

  • Pending: the Current list is hidden.
  • Released: its Current list shows the most recent released child revision.
  • Canceled: the Current list displays the child item's revision that was valid at the point when the parent item revision was canceled.

Child item properties

Parts on structures generally require the quantity, units of measure, and possibly reference designators or other notes. Supporting documents do not allow quantity or units of measure.

Find-item numbers

A find-item number is a child item's "address" on the structure and provides:

  • A point of reference between revisions, or between similar parent items.
  • A way to identify items depicted on a drawing without including the actual item number on the drawing, thereby abstracting the item's purpose from its identification.

To show the differences between two consecutive revisions of a parent item, structure markups refer to a particular find-item "address", and reference that find-item number in removing one item and adding another. In order to ensure traceability between revisions, find-item numbers cannot be modified after the parent item's initial revision has been released.

Sources

Source item restrictions

Only parts can be sources for a part, and documents can be sources for a document. You will not be able to drop an item onto the Source tab's Markup list of the opposite item class.

Rank numbers

A rank number typically is assigned to parts and indicates the designer's preference of one supplier over another supplier. Rank numbers, unlike find-item numbers, can be changed after the item has been released. If an item class allows an item to be modified without processing a change, then the rank can also be changed without a change.

Your own organization can be the source for another item. This is very effective when you are switching from one numbering system to another, or have discovered multiple inventory numbers for the identical item, or are merging two different companies' identification schemes.

Markup and Current lists

As with the Structure tab, modifications to a pending parent revision are made on the Markup list of the Source tab. This list is frozen when the parent item is released. The Current list on the Source tab continues to reflect revision-level changes to source items automatically. When the parent item is canceled, the Current list is frozen at that point.

Appears on ("where used", "where changed")

You can view all parent items where an item (or item revision) is used. By opening the item shown, you can see that parent item's own parent items.

In addition, you can discover which changes have affected the item, including the changes that released or canceled the item. Expanding the change will show the dispositioning information.

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Help topics describe the most current PDXpert PLM software release, and may differ from earlier releases.