Pocket querries are generated automatically and get a running number provided by the server. Created pocket querries (ZIP file) includes two GPX files (one file showing the caches and one file showing the waypoints) which can be individual renamed (e.g 123321.gpx -> brussel.gpx), before uploading to it to your GPS device. By this you can easily distinquish between uploaded GPX files and delete GPX files, which are not required anymore.
If you want to make changes within the GPX file, it will take some additional steps.
Every GPX file can be edited via the text editor. By this you have to change the ending of the GPX file (123321.gpx) in a TXT file (123321.txt). Afterwards open the file with your text editor and make changes to the file. Rename the file afterwards (123321.txt -> 123321.gpx) and upload it to your GPS device.