The following applies to at least version 3.50 of Spectrum Survey but may differ for versions earlier than 3.25.
(Winzip version 10.0)

 Archiving

you'll need to store the following 3 items:

1. the project file as created by Spectrum Survey:   e.g.  ...\Spectrum Projects\Holsworthy.spr
2. the project directory (folder) as created by Spectrum Survey: e.g:
    C:\Program Files\Sokkia\Common\Spectrum Projects\Holsworthy     with subdirectories Data, Database, Results
3. the raw data ( only if not present in the Data subdirectory already - see Note below)

The archiving is done easiest by using Winzip: highlight the  .spr file and the project folder, right click, Winzip, Add to ZIP file, e.g. holsworthy.zip, browse to where the ZIP file should be stored, go!

After you've archived the project, you can delete the project, either by removing the project file and the project folder with subfolders or within Spectrum Survey, in the Tools\Project Editor menu.

 Restoring

The raw data, database and results folders need to be in the same location as when the project was saved:

Highlight the ZIP file, e.g. holsworthy.zip , right click and  Unzip to...   c:\
  ( don't unzip to 'here' ! )
The subfolders will have the correct path, you may want to move the .spr file to the same location as other project files

 Note

It's handy to first create a project in Spectrum Survey, this will automatically create a Data subfolder and only then copy your raw data (.pdc files) into that Data subfolder.