Text displayed on the vertical axis of the calendar

Question

I want in the the left frame of the calendar (where the hours are shown) to put some letters or titles. For instance A1, A2, A3 etc.

in calendarview.js

  axisFormat: userDefaultTimeFormat,

and

var userDefaultTimeFormat = jQuery('#time_format').val();
    if(userDefaultTimeFormat == 24){
        userDefaultTimeFormat = 'H(:mm)';
    } else {
        userDefaultTimeFormat = 'h(:mm)tt';
    }

I have changed

userDefaultTimeFormat = 'H(:mm)'; 

to

userDefaultTimeFormat = 'A1 H(:mm)';

This only changes the first quarter..

I want the same o the remaining quarters (9.15) A2, (9.30) A3, (9.45) A4. (Only the characters no time)

How can i do that?