Field help (AGACACCSHO) 

The call code is a keyboard short cut associated with the account. It can be entered in the place of the general account number wherever a general account is required. The shorter length (4 characters) than the account general, its use makes it possible to accelerate the entries.
A call code must be an alphanumeric code of a minimum of two characters, the firs character must be a letter.
In this case of a control account, this field contains the control account. (For example C1 for a control account).