I'm writing a program that involves processing G-codes.

I've tried to read up the details of G71 but am a little bit confused.

If you look at the description, for example here:

Fanuc G71 Turning Cycle - Helman CNC

Code:
N50 G00 X106 Z5 M3 S800
N60 G71 U10 R10 
N70 G71 P80 Q90 U3 W0 F0.25
N80 G00 X60
N90 G01 Z-75 F0.15
N100 G00 X200 Z100
N110 G92 S1200
N120 T3 G96 S150 M03
N130 G00 X106 Z5
N140 G70 P80 Q90
N150 G00 X200 Z100
N160 M30
What happens after G71 stops executing line N70, i.e. after it has performed lines the lines/blocks 80 and 90 number times?

Will the code then "fall through" those same lines as they 'happen' to be there?

Is it customary to have profile there?

Mandatory?

And if they get executed doesn't that make G70 at line N140 superfluous as that has been cut already albeit at different speed?

thanks!