The catalogue is where PMIO stores information about every image it sees. When you navigate to a location that PMIO has never seen before, the images at that location are analysed. During this process, the address of each image is added to the catalogue, along with a unique identifier called the file contents id. The catalogue allows PMIO to:
The catalogue makes it possible to browse your CDs or other removable media without having to insert them into your computer. Once you find the images you want to look at, PMIO will prompt you to insert the required volume. All this assumes that PMIO has scanned the volume in either the Batch Engine or the browser, so that it has had a chance to catalogue all the information.
The catalogue typically takes up a few megabytes of hard disk space. If you want to reduce the amount of space it uses, you can periodically use the Tidy Catalogue function.