A Mezzanine Card or PMC is a printed circuit board assembly manufactured to the IEEE P1386.1 standard. This standard combines the electrical characteristics of the PCI bus with the mechanical dimensions of the Common Mezzanine Card or CMC format (IEEE 1386 standard).
A mezzanine connector connects two parallel printed circuit boards in a stacking configuration. Many mezzanine connector styles are commercially available for this purpose, however PMC mezzanine applications usually use the 1.0 mm pitch 64 pin connector described in IEEE 1386.
Additional standards exist that define variants of the standard PMC. This is a short example:
- PMC-X (PCI-X PMC)
- PPMC
- CCPMC
- XMC (or "Switched"
- FMC (just FPGA Mezzanine)
tldr; mezzanine cards with a certain standard will work on mezzanine boards with the same standart. Function depends on firmware (of both).