Layer stackup

Layer stackup is an important and sometimes contentious issue in the deisgn of a multi-layer board.
If I give the fabricator enough information will he be able to manufacture my board? Well possibly, any material specs you give are only valid if that material is stocked by your fabricator, substitutions are often made and different materials will have different characteristics.

Obviously, the fabricator needs to know which layer goes where in the stackup and the more information given about those layers the better the chance your board will perform to expectations. The finished thickness of the board (after pressing) is most important, check value with the fabricators capability. The positions of cores and prepregs should be given with their thicknesses and any additional useful information such as Dk value and don't forget about the thickness of each of the copper layers.

PCB designers should know more about PCB substrates

In today’s complex world of electronics design PCB designers need to understand which substrates materials to use and when.
This understanding will bring benefits in reliability and savings in cost. No more broken vias, better impedance control, less timing skew problems and no more mistakes made in selecting unnecessarily expensive grades of FR-4 or polyimide.

IPC-4101B Specification for Base Materials for Rigid and Multilayer Printed Boards (including RoHS compliancy data) is the most comprehensive stanadard available for making sure your impedance calculations have realistic figures and when the need to arises to talk to your fabricator about layer stack-up, borad thickness etc then you can readily appreciate how any changes may affect your design.