Hello Marios
Actually, if you take a closer look at Type 3 and Type 4 LSAs, you will find that they are not flooded throughout the whole AS scope. Looking at the related lesson about OSPFv2 LSAs, you can see that both are generated by an ABR that receives a Type 1 LSA. They are flooded to the rest of the network, but not in the OSPF area from which the Type 1 LSA is received.
The only LSA that truly exists throughout the whole AS in all OSPF areas is a Type 5 LSA, and it is the only one that begins with 0x4.
I hope this has been helpful!
Laz