You, the user, specify the location of a document when saving it for the first time or when using "Save Document As...".
All other settings, preferences and any objects that live in the "Application" document are stored in a predefined container in the user's home directory.
The root directory for these settings is ~/Library/Application Support/Royal TSX
Please note that the "~" character refers to your user's home directory which translates to /Users/YourUserName/.
Here's a short explanation of what each of the files and subdirectories in this folder are used for:
~/Library/Application Support/Royal TSX/UserPreferences.config
Stores Preferences, Settings and the content of the "Application Document".
~/Library/Application Support/Royal TSX/License.xml
Stores your Royal TSX license information (if registered).
~/Library/Application Support/Royal TSX/AutoStartFiles/
Used to store references to the documents that were open when the application was closed the last time. These references are used to re-open documents on the next application start.
~/Library/Application Support/Royal TSX/CrashLogs/
Used to store crash logs. This directory is scanned on every application start and the Crash Reporter will pop up if at least one crash log is found.
~/Library/Application Support/Royal TSX/Logs/
Stores log files created by the application. You can enable File Logging by going to Preferences - Logging - File Logging.
~/Library/Application Support/Royal TSX/Plugins/
Contains several subdirectories which are used to store installed plugins and their settings.
~/Library/Application Support/Royal TSX/Plugins/Installed/
As the name suggests, installed plugins are stored in this directory.
~/Library/Application Support/Royal TSX/Plugins/Settings/
Used to store plugin-specific settings.
~/Library/Application Support/Royal TSX/Plugins/WaitingForInstall/
When a plugin is being installed or updated, it will be transferred to this directory until the application is restarted. The plugin is then, upon successful inititialization being copied over to the "Installed" directory.
~/Library/Application Support/Royal TSX/Plugins/WaitingForUninstall/
When a plugin is being uninstalled, a reference to it will be created in this directory. When the application is restarted, Royal TSX tries to resolve these references to installed plugins which are then in turn being deleted from the "Installed" directory.
~/Library/Application Support/Royal TSX/RecentFiles/
Used to store references to recently used documents. These references are resolved and displayed when using File - Open Recent Document