Here's an explination of how i use Level of Detail (LOD) vs View Rep (VR).
the use of these features for me is mostly geared towards my needs in a 2d drawing later. Lets say i have a Master.iam that has Sub1.iam, Sub2.iam and Sub3.iam.
Master.iam will be used in 3 different drawings, 100.idw, 200.idw, and 300.idw. Each drawing having there own uses/needs of what information is relevant. Usually 100.idw with be a basic over view "General Arrangment" and the other drawings may show more detail of how to build the project.
I use LOD's to suppress unessary parts for each drawing setup, a 100-LOD, 200-LOD, 300-LOD. This limits the total numbers of parts loaded into memory while i'm working in a drawing file. If you use a base view with 100-LOD and a secound base view of 200-LOD it will double the amount of parts you have in the memory for the drawing, so only use one LOD for the entire drawing. Also you can not change the assigned LOD of view after you place it.
Example, 100.iam will only use 100-LOD wich only shows the exterior parts so the part count is really low.
Now in 200.idw, I use 200-LOD that includes all the parts that are needed, but i need multiple VR settings to visually turn on/off parts for different views in the drawing "All on", "No bolts", "Part A & B off", "Sub3 Only". VR's are awesome becuase I can create a base view with "All on" VR that shows everything, and pull a section or detail with the setting as "Part A & B off" to only show a few relevant parts. Each view can independently assign VR's, but they all come from one LOD.
In 300.idw VR's allow me to use only Master.iam with 300-LOD "All on" VR on 1st page with a full BOM and labeled item numbers on parts, and on the 2nd page show base view 300-LOD "Sub3 Only" wich only has the Sub3.iam visible. The allows me to detail Sub3.iam while maintaing BOM item numbers from the Master.iam BOM and prevent duplicating the Sub3.iam part counts in memory.
also VR settings can be applied to drawing BOM filters.
The drawings will use one LOD and a (shared) mix of VR's.
hope that helps
