XYZBook
With this mod, saving coordinates becomes simple and convenient. You no longer need to manually write down numerical values - just specify the location name, and the mod will handle the rest. Coordinates are automatically added to the book with color coding depending on the dimension: green for the Overworld, red for the Nether, and purple for the End.
How to Use
Take a book and quill and rename it on an anvil so that the name contains "XYZ".
Book Interface
The "Sign" button is replaced with "New Entry". Click it, enter the location name, and confirm with the "Done" button. An entry with current coordinates colored according to the dimension will appear in the book.