The saved view contains the viewing projection, i.e. the orientation of the structure, the list of which objects are to be displayed, the bond mode and radius, the atom mode and resolution, and all of the worm, helix and sheet parameters. Finally, they contain the colors for all atoms and objects.
View files are primarily meant to be used in a single session, not as a means of saving information between sessions. As such, view files do not contain atom or vertex coordinates, or the definition of any non-standard worms you may have created. The information that is saved consists primarily of the graphics projection, and the object colors. However, view files are not normally deleted at the end of a session. This provides a quick-and-dirty way of returning quickly to a particular state between sessions, if the same conditions apply, which is to say that the same PDB files are read in, and the same surfaces are created. If there is a -match in the number of atoms between the current session and the view file, only a limited amount of information is read from the view files, and no colors are read. Similarly, if there's a mismatch between the current number of surface vertices and the number stored in the file, the vertex colors are not read from the file.
View files may not be compatible between different versions of spock, but every attempt has been made to allow the different versions to share data. However, since these are binary files, they may not be shared across different operating systems or machine types. Spock attempts to detect incompatibilities in operating systems, but may not always be successful, and reading in a view file from an incompatible system could cause a crash.
Spock session files (§6.1.2) also provide a way to return to a previous state, but session files save much more information than view files, and are consequently larger. For switching between views, use view files, and to save your work between sessions, use session files.