What does ‘a’ and ‘e’ indicate in the surface texture symbol shown below?

Production method, roughness value

Roughness value, machining allowance

Machining allowance, sampling length

Heat treatment method, sample length

What does ‘a’ and ‘e’ indicate in the surface texture symbol s

1.	What does ‘a’ and ‘e’ indicate in the surface texture symbol shown below?
A.	Roughness value, machining allowance
B.	Production method, roughness value
C.	Machining allowance, sampling length
D.	Heat treatment method, sample length
Answer» B. Production method, roughness value