TITLE is a primary sort field (1)
click on the letter "P" (2)
the library catalogue section that starts with "P" is displayed (3)

The letter bar commands are listed in the Record Grid popup menu.

You can decide where the letter bar is displayed. You can hide the letter bar.

AUTHOR is a primary sort field (1)
click on the letter "O" (2)
the library catalogue section where AUTHOR starts with "O" is displayed (3)

CALL is a primary sort field (1)
click on the letter "P" (2)
the library catalogue section where CALL NUMBER starts with "P" is displayed (3)

Question: I would ask that the Alpha index be added. This way you can go quickly to where you want to go. I very often review my library items by title or author, in this case would like to jump to the section with the selected letter.

Letter tabs feature is added to version 3.2. All tables can display the letter bar option.