Note for us

Hello embedded's Bigboys

i need for you to confime me if that true 

if i wrong with any sentence correct to me to spread the knowledge 

every error  in assembler

has code 

like A45 : undefined symbol (pass~2)

i have two question

1. first one :tell us about for error code and decription of it
2. second one :in A45 what is mean of this (pass~2)

Thank you guys