SAP Chart of Account

It defines the structure of G/L accounts.  It is a list of G/L accounts
used by one or more company codes. In that Chart of account you have to specify
the length of G/L accounts.
In SAP all the entries are document oriented. so from the balance sheet of
any entry you can identify the root of an entry. so it's like a flow chart in
computer terms. 
There are threee types of Chart of Account are there.
1.Operative Chart of Accounts
2.Group of Chart of Accounts
3.Country Chart of Accounts.
1.Operative Chart of Accounts is a Chart of Account you use for the company
code.
2.For different chart of accounts(operative COA) for different company code,
you can group the chart of account into one chart of account for internal
reporting, but cross company code controlling is not possible, because of
different chart of account for different company code. 
3.For different country you can have different reporting system. so for
different company code you can have different company code, but can have same
Operative Chart of account, so cross company code controlling is possible.