When drawing layout from schematic, there is a PR Boundary option in the 'Generate All From Source' dialog box. It is depicted as a cyan field, that covers other layers. Placing a transistor (or ony other cell) on it makes it invisible (the PR boundary covers it). What is its purpose and what does the abbreviation 'PR' stand for? The PR Boundary cyan layer is not even present in LSW window, but there is a prBoundary layer of violet color.
prBoundary stands for "Place and Route Boundary". It is intended to be the region within which placement is done, and where routing is constrained to.
In IC61X, prBoundary is a special object - it's seen under the "objects" the LSW. The colours and fill patterns used to display it though are those associated with the prBoundary layer in the tech file - so you'd need to use the Display Resource Editor to see how the prBoundary layer is displayed (maybe "drawing" purpose or maybe "boundary" purpose). Any normal shapes on prBoundary are ignored by the tool.
In IC5141, prBoundary was just a shape on a layer - and it may be "drawing" or "boundary" purpose (my guess is that's why you're seeing two different colours). It may be that the packet defined for it in your display.drf has been set with a fill pattern - normally it's left with no fill pattern. You can then use the set valid layers (in the LSW) to control whether these prBoundary layer-purpose pairs show up in the LSW, and you can use the Display Resource Manager to control the appearance.
In both cases the boundary/shape object are important because they are used by the tools to guide various things.
In reply to Andrew Beckett:
Bringing this thread back to life....
In IC6.1.X, is there a gds layer number for prBoundary? I don't see any in the dumped techfile.
Is it because it's a "special object" there's no gds layer number for it?
grep prBoundry from techfile returns :
( prBoundary drawing ) ( prBoundary label ) ( prBoundary boundary ) ( prBoundary drawing prBoundary_drawing t t t t t ) ( prBoundary label prBoundary_label t t t t nil ) ( prBoundary boundary prBoundary_boundary t t t t nil )