What does hierarchy level means in the layout. As I increase the level number, new layers are visible. When level number is 1, only bonding box is visible. Does it signifies anything important?
First, if you don't already know it's probably a good idea to read up on what a GDS cell is, and what it means when a GDS (or OAS) cell is "instanced" inside another cell. Once you understand that, proceed to the following explanation:
Say you have a parent cell named "PARENT". Inside that parent cell are is a child cell named "CHILD" and also one arbitrary polygon. Inside of "CHILD" there is another child cell called "GRANDCHILD".
OK, in this example when hierarchy is set to 1 you will only see bounding box of PARENT. When set to 2 you will see that polygon inside PARENT, and will also see CHILD's bounding box. In other words, you are peering in to PARENT to see what is inside. What is inside? Well, one polygon and one cell called CHILD. But you won't see GRANDCHILD because that is not directly an element of PARENT. Next, increase hierarchy to 2 and you will see all that you saw before plus you will see inside of CHILD, and now you see that it has one thing inside of it, shown as a bounding box with "GRANDCHILD" printed on it. (Note that you can use +,- keys to traverse the hierarchy.)
So this is useful for looking "into" a layout down to a certain hierarchy level. However perhaps more importantly it is useful for SELECTING something within a layout. Say you want to select "CHILD" for some reason (like, you want to press "q" to see/modify its properties). To allow us to do this, press F3 and toggle "Select top level objects only". If it's set to true then no matter what hierarchy level you have set, you will never be able to select CHILD. (This is useful; you don't always want to be selecting CHILD, you might want to be selecting something else.) If it's set to false, you will only be able to select child if hierarchy is set to 2 (but not 1 or 3).
One other tip is to right click on a cell > Show as new top, if you just want to view only CHILD (and not CHILD instanced in PARENT).
Play around a bit and post here if something else doesn't make sense.
Comments
Heh. Yes it's all-important. :-)
First, if you don't already know it's probably a good idea to read up on what a GDS cell is, and what it means when a GDS (or OAS) cell is "instanced" inside another cell. Once you understand that, proceed to the following explanation:
Say you have a parent cell named "PARENT". Inside that parent cell are is a child cell named "CHILD" and also one arbitrary polygon. Inside of "CHILD" there is another child cell called "GRANDCHILD".
OK, in this example when hierarchy is set to 1 you will only see bounding box of PARENT. When set to 2 you will see that polygon inside PARENT, and will also see CHILD's bounding box. In other words, you are peering in to PARENT to see what is inside. What is inside? Well, one polygon and one cell called CHILD. But you won't see GRANDCHILD because that is not directly an element of PARENT. Next, increase hierarchy to 2 and you will see all that you saw before plus you will see inside of CHILD, and now you see that it has one thing inside of it, shown as a bounding box with "GRANDCHILD" printed on it. (Note that you can use +,- keys to traverse the hierarchy.)
So this is useful for looking "into" a layout down to a certain hierarchy level. However perhaps more importantly it is useful for SELECTING something within a layout. Say you want to select "CHILD" for some reason (like, you want to press "q" to see/modify its properties). To allow us to do this, press F3 and toggle "Select top level objects only". If it's set to true then no matter what hierarchy level you have set, you will never be able to select CHILD. (This is useful; you don't always want to be selecting CHILD, you might want to be selecting something else.) If it's set to false, you will only be able to select child if hierarchy is set to 2 (but not 1 or 3).
One other tip is to right click on a cell > Show as new top, if you just want to view only CHILD (and not CHILD instanced in PARENT).
Play around a bit and post here if something else doesn't make sense.