Journal Entries for Contract Accounts

[Shunmas]

Asalam-o-Alaikum !

I am doing contract accounts from Sir M.A.Ghani's Advanced Accounting book.

Sir Ghani says that a contact account is basically a profit & loss account (from a contarctor's point of view). All expenses are debited and income credited.

That is fine, I understand this concept.

BUT the entry for purchasing raw material is

DR. CONTRACT A/C
CR. RAW MATERIALS A/C

Now why would we credit the raw materials?

Is it same like in general business that when we buy goods (perpetual inventory system), we debit inventory and then using transferring entries, we transfer the inventory to P & L ?

Is this concept is being followed in the above the Journal entry?

Thanks