Update sequence is the display order in which the references, models, and sheets are updated in the view windows. When updating a view, the application follows, by default, the update sequence set by these configuration variables: MS_REF_MASTERFILELAST_SHEET, MS_REF_MASTERFILELAST_DRAWING, and MS_REF_MASTERFILELAST_DESIGN . By default, references in the sheet model and drawing model are visible on top of the master sheet and drawing models; whereas the references in a design model are visible on top of the master design model. The effect of these configuration variables will be seen only on models created using MicroStation V8i (SELECTseries 1) or later editions.