The "E" tells you it's an E glass blank (It's been built is a few different Glass types and Glass/graphite combos over the years), the "F" says it's a faster actioned blank.
The last numbers are the blank's power in relation to each other.
The MB has been the series designation for Many years, "M" means mooching/livebait action, the "B" means it's a blank.
The GLB blanks are G 1000 graphite live bait blanks. Any first set of letters with a "P" in it is a popping rod blank.