Internal. The ultimate sources of variation, the source of new heritable characteristics in populations and species, are due to mutation and recombination in chromosomes, genes, DNA.
Zone VE is the flood insurance rate zone that corresponds to coastal areas that have additional hazards associated with storm waves. Mandatory flood insurance requirements apply. Zone X and Zone X-500 are flood insurance rate zones that are outside the flood plain or with average flood depths of less than 1 foot.
It essentially states that you are in a flood zone and could potentially flood up to the BFE based on simulated models and hydraulic analyses, therefore regulations restrict you from doing certain things below the BFE. Mandatory flood insurance purchase requirements apply.