How can you place alignment markers on a PCB using Protel DXP.
I am designing a multilayer board and would like have the layers properly aligned. So how do i put in some alignemnt markers during the PCB design such that the layers are indeed aligned when fabricated.
Fabrication layer and panel alignment is usually the responsibility of the board fabricator CAM operator. The CAM operator will define "tooling holes" that are drilled in the panels outside your board outline, and through which dowel pins are placed. The dowels remain in the panels to keep them aligned during the layup and pressing phases. You would have no way of knowing what size dowels your fabricator uses, or whether or not he was going to panelize your board with another customer's board to increase his production. For that reason, you wouldn't be able to define the tooling hole size and position.
Alignment marks for automatic component placement are inside the boundaries of the board, and are called fiducials. You can make fiducial components for your own use - they are just small surface pads with solder mask openings around them. There is a detailed discussion at: https://www.tkb-4u.com/articles/other/fiducial/fiducial.php