A-code what’s going on?

Hi.
I’m a beginner to CNC coding and am having trouble understanding the “A-code” (rotation around the X Axis)

This is a sample of a section of the profiling cycle on a job I have done recently.

G72 R0.5 W1.5 ;
G72 P11 Q12 U0.0 W0.0 F0.2 ;
N11 G01 Z0.0 ;
N12 G01 X30.0 ;
G0 X52.0 Z1.0 ;
G01 Z0.0 F0.2 ;
X55.0 R1.3 ;
X58.0 A135. ; ( A-code #1)
Z-11.5
X61.0 A135. ; (A-code #2)
G00 X450. Z450. ;
M01 ;

I understand that it creates a chamfer of 45degrees but I’m at a loss to understand where it gets the length of the chamfer data from.

Any assistance would be great fully appreciated.