Acceleration and deceleration of the movements

At the end of the movement, use the ACC command for acceleration. I have never known there to be a decel command.

The ACC expression, along with the number that goes with it... affects both the acceleration and deceleration ramps in the Fanuc robot, as it may pertain to a particular position instruction.
Don't forget to check or set the unitless scale for your ACC expression in MENU- SYSTEM- Config window, Max of ACC instruction and MIN of ACC instruction.

I agree with Cobenson. I am not aware of any way to specify deceleration ramp only using normal TP Programming language.

Just a note, ACC Can go up to 150

First, check or set the scale in MENU-System-Config window: Max. of ACC Instruction and Min. of ACC Instruction.
Let us say you have chosen a scale (a range) of 50 to 150

12: L P[4] 2000 mm/sec CNT 100 ACC 150
reach speed with strongest acceleration/deceleration ramp

Or

17: L P[6] 1500 mm/sec CNT 100 ACC 50
reach speed with weakest acceleration ramp