Here is an answer from one of the experts of here:

"I have not found an automatic method of incrementing the current active

angle by 90 degrees using a function key. The only function key assignments

that could work "on the fly" are fixed absolute entries. For example, you

could assign 4 function keys in this manner; Alt-F5 as AA=0; Alt-F6 as

AA=90; Alt-F7 as AA=180; and Alt-F8 as AA=270; Then you could press the

appropriate function key for the absolute rotation specified. Unfortunately.

if your current Active Angle is not at 0, 90, 180 or 270, this will not

increment the value by 90 degrees.

Another means of dealing with this situation is to utilize AccuDraw as the

input method. AccuDraw acts as an on the fly "Ortho lock" with automatic

snapping to the horizontal or vertical axis when placing elements. And in

the case where the current Active Angle is not at 0 degrees, the AccuDraw

compass will still allow you to move or lock your cursor at any angle 90

degrees from the current active angle. If you happen to be placing a cell or

text and want to rotate the cell while placing it at 90 degree increments to

your current active angle setting, Press the function key F11, then the

key-in shortcuts "RZ", (Which stands for "Rotate Z axis"). Continue pressing

the shortcuts "RZ" to dynamically rotate the cell or text by 90 degree

increments. Dismissing AccuDraw is accomplished by pressing the letter "Q".

There is a peculiarity in MicroStation V8i Select Series 2 that requires you

to press the letter "O" before pressing "RZ". This was not the case in

MicroStation V8. Not sure why."