Often, during the review stage of a project, different changes might be necessary such as:
– New details (views) added on the drawing to provide additional information
– Model modifications such as element geometry, element position, material, new elements

Model modifications affect the existing drawings. Since there are several people involved in the review process, it is useful to keep track of the changes made.

 Standard practice 

According to standard practice in maintenance of engineering drawings, changes made in the model during the review stage of a project are identified using a number or a letter code and are listed in the revision table on the affected drawing. For each revision level, the revision table lists the reviewer (author) and a short description of the change made. Additionally, revision clouds are used to draw attention on modified areas of the drawing.

 CAD techniques 

Using simple CAD software, the elements are modified and revision clouds are drawn manually – a task that requires patience and significant attention to mark and then locate the changes in the drawing. The revision table is drawn using simple entities (lines and text) and updated manually. Additionally, a document management system can be used for drawing revision control.

 Advance Steel – Easier revision management 

Detailing software like Advance Steel allows keeping track of the changes in drawings similar to traditional revision control, but with a lot of improvements in the workflow:

• Drawing update
• History and backups
• Tracking of changes in the revision table
• Marking changes using revision clouds

Read more here