All 'Event' nodes in the Message View show events used internally by the FPGA and 1480A PC-side software. Some events mean things like device connection while other events like F1 means end-of-stream-marker. The F1 end of stream markers are used to flush out all the data from the FPGA and SDRAM to the PC software. When the PC software detects the F1 markers it knows that the end of the captured data has been reached and that the parsing can stop.
There are also F0 markers that mean that the SDRAM FIFO has been filled up during capture. The E0 marker very first in the data stream is a version marker that allow us to handle eventual future data stream format changes.