The C. and S. are Lewis' first and middle names. They stand for "Clive" and "Staples".
Immigration and Customs Enforecement
Clive Staples Lewis
Computer Aided (or Assisted) Drafting.
The initials stood for 'Clive Staples' but throughout his life Lewis was referred to by family and friends as 'Jack'. The reason for this was that when he was just four years old, the family dog (named Jacksie) was run over by a car. Young Clive decided then he would only be called Jacksie - and it was only as he grew older that his mother was able to cionvince him to at least change it to Jack.
In politics DLC stands for Democratic Leadership Council.
C. S. Lewis' full name is Clive Staples Lewis, but was often called "Jack" by family and close friends.
The actor and voice actor D.C. Douglas apparently sticks to just the initials because no one has released what is on his birth certificate (born February 2, 1966).
casting society of america