It looks like you are looking for a PDF document related to the (part of the Nokia 7x50 series, like the 7450 ESS, 7750 SR, and 7950 XRS).
The stands for FPGA State Machine Fast — it is a hardware acceleration module used in Nokia's IOM (Input/Output Module) cards, specifically for fast Layer 2 VPN services (VPLS), MAC management, and packet replication. nokia fsmf module pdf