- View Ports are portals displaying Design Layer content on a Sheet Layer
Limit the View by a Crop Object
A drawing's layout can be arranged on a Sheet Layer using several View Ports. Each View Port, in principle, displays all content of all the Design Layers in a document. The display of the View Port will be limited in size by the reach of the objects in the Design Layers or by a Crop Object.
Filter Layer and Class data
Before the data is displayed it goes through a 'filter' that can be set in the Object info Palette. In this 'filter' Design Layer visibilities can be set to either Show, Gray or Hide their content. Classes have the same View Options as Layers, but can also be changed in their appearances, by setting the Class' attributes, this is done independently from the global Class Attributes as used while working in the Design Layers. This change in attributes is valid only for the selected View Port(s). These 'filter' settings can be copied from one View Port to the next using the Eyedropper tool. Make sure to check its settings as it is, by default, set to copy the Layer visibilities, and usually you don't want those copied.
Each View Port can be set to display the drawing on a scale independent of the scale in the Design Layers, but is limited to displaying the content in one scale per View Port.
Dissecting a View Port
Taking a closer look at a View Port we see it consists of three different parts:
- a: The actual display of the Design Layer(s) and Class(es)
- b: The Crop object
- c: The Annotations
These parts are accessible by double clicking the View Port, or by choosing Edit View Port under the Modify menu, when the View Port is selected.
Since multiple View Ports can use a single part of the Design Layers for displaying on different scales, it is sometimes preferred to add data, that is used for only one of the instances, where it is actually needed: on the Sheet Layer. The Annotation part of the View Port has the advantages of keeping the data together and editing can be done in same, real world, scale of the Design Layer(s). Try to avoid using the Annotations, in general speaking: Adding data is done, as much as possible, on the Design Layers. Sheet Layers are to be used for arranging your drawing's layout. 
To limit the size of the View Port to display only a portion of the Design Layer(s) a Crop Object can be used. There may only be one object per View Port and it must enclose an area to display through. So the Crop object may be a Rectangle, Circle, Oval, Polyline or Polygon. The Crop Object can be made invisible by setting its lineweight to zero, or by giving it a special Class that can be set invisible in the Object Info Palette.
Except by setting the 'filter' in the Object Info Palette, the display can not be edited. Editing the View Port and choosing for (a:) 'Design Layer', opens the Design Layers and sets (if checked (d:)) the Layer & Class visibilities similar to the settings of the View Port. This is, especially in larger and more complex Vectorworks files, a fantastic way of navigating the file when applying some final edits.
- Of course it is also possible to place annotations 'on top of the Viewport', added to the SheetLayer , but are restricted to a 1:1 scale and are not part of the ViewPort.