The keytrack contains information from the constituent records in Raiser's Edge. This information is then used to match the constituents with the paper declarations / forms that were sent to Blackbaud to be scanned. Once the scanned images have been matched to the relevant constituents, they are available to view either from the constituent records in Raiser's Edge or from the scanstore web site. See How to view scanned images for more information on how to set this up.
If paper declarations are sent to Blackbaud on a regular basis to be scanned then you should consider sending your Keytrack so that these new declarations can also be matched to the constituent information in Raiser's Edge.