Comparing modules

Use the Module Comparison wizard to compare two modules and identify objects that have been inserted, deleted, moved, or edited. For example, a set of requirements for a project might be updated several times by the customer. You can import the updated requirements into a new IBM® Engineering Requirements Management DOORS® (DOORS) module, and then compare the new module to the original module.

Before you begin

Open the current version of the newer module in exclusive edit mode. The wizard assumes that the module that it is run from is the most recent, and marks up the text accordingly. The wizard can add a column to the module to display changes with markup. Optionally, create a view to add the column to. The view must include the main column.

About this task

The wizard only compares plain text. Rich text formatting, pictures, and OLE objects cannot be compared. OLE objects embedded in text are also ignored when the text is compared.

Approximate matching techniques are used, which work best when about 75% of the heading structure of the modules that are being compared is identical.

  • Identical and almost identical objects are matched
  • Changes are displayed in a column in the new module with markup
  • Links are created between objects that are matched.
  • When the comparison is complete, a filter can be applied to both modules so that only objects that have not been matched are displayed.
The comparison is performed in four stages. Stages one and three are compulsory; stages two and four are optional. You can select the attributes that the wizard compares.
Table 1. The stages of a module comparison
Stage Description
One Matches objects that are identical. Objects that have been moved are not matched during this stage.

If a large number of objects remain unmatched after this stage is complete, the remaining phases are slow.
Two Matches objects that have changed.

Objects are matched if they appear in the same order in both modules, and if some of the words being compared are identical. Objects that have been moved are not matched during this stage.

You can define what percentage of the text must be identical for objects to be matched. The percentage is calculated by the number of identical words in the object, and is approximate.
Three Compares the remaining objects and matches identical objects, regardless of their position in the module. Objects that have not been edited, but have been moved are matched during this stage.
Four Compares any objects that have not yet been matched, and matches them if some of the text being compared is identical.

Objects that have been edited and moved are matched during this stage.

You can define what percentage of the text must be identical for objects to be matched. The percentage is calculated by the number of identical words in the object, and is approximate.

Procedure

  1. Click Tools > Compare Modules, and step through the wizard.
    For more information about any of the screens, click Help.
    The comparison starts when you complete the wizard. When the comparison is complete, a dialog box is displayed, which provides information about the comparison.
  2. Click Close.
    If you selected to filter the modules to show unmatched objects, the filter is applied.

    If you ran all four stages of the wizard:

    • Objects that have been inserted since the older module was created are shown in the filter in the newer module
    • Objects that have been deleted since the older module was created are shown in the filter in the older module
    Note: Objects that have more unmatched text than you specified in the Maximum percentage difference in matched objects box are also shown.
  3. Adjust the linking if necessary. You can manually link any objects that have not been matched by the wizard, or delete any links that you do not want.

What to do next

If the wizard added a column to display changes with markup, and you want to add the column permanently, you need to save the view.