Change Highlighting

Change Rules control how Design and Annotation elements that have been changed are drawn on a Draft View and are similar to Representation Rules. Each Change Rule can be specific to a given type or types of element, or named elements. Change Rules refer to Change Styles, either Design Change Styles or Annotation Change Styles, depending on whether the changed element is a Design element or an Annotation element. The attributes of the Change Styles define the way in which changed elements will be drawn. Generally this will be by altering the drawing styles and colours used. Pieces of text may also have their font changed, be underlined, or be enclosed within a specified style of parentheses. for further information about styles and colours see Colors and Styles. For information about Representation Rules see Graphical Representation.

In order to determine whether Design and Annotation elements have changed, it is necessary to compare the relevant databases at two points in time. One of these two points is always the current time. The other point used is a Comparison Date. The concept of Comparison Dates is discussed in Comparison Date.

Design Change Rules (DCRULE) and Annotation Change Rules (ACRULE) are stored in Change Rulesets (CRST), which in turn are owned by Representation Libraries (RPLB).

RPLBs are also used to store Design Change Styles (DCSTYL) and Annotation Change Styles (ACSTYL). The reference from a DCRULE to a DCSTYL is made by its DCSTYF attribute, and the reference from an ACRULE to an ACSTYL is made by its ACSTYF attribute. When a VIEW references a CRST, the reference is made by its CRSF attribute.

Figure 10:1. Change Rules Database Hierarchy

The hierarchy of database elements for Change Highlighting is similar to that for Representation and Auto-hatching and allows company or project standards to be imposed. However, unlike Representation and Hatching Rules, Change Rules cannot be owned directly by a VIEW and there are therefore no local change rules.

Once the Rulesets and Styles have been set up, it is just a matter of setting the VIEW attribute CRSF to point to the Ruleset that you wish to use, defining a Comparison Date, and issuing an UPDATE command with the SHOW CHAnges option (see UPDATE Command, SHOW CHANGES Option and Error Messages).