Correct. An obstacle of less than 300ft a.g.l. (e.g. a temporary mast) doesn't have to be notified to the CAA - so the MEF allows for this. For example, Lundy Island has a spot height of 466ft - but an unknown obstacle of 299ft might exist, so the MEF is (466+299) = 765ft, which is rounded up to the 08 shown on the chart.