“A heliport beacon should be provided at a heliport where long-range visual guidance is considered necessary […] or identification of the heliport is difficult due to surrounding lights.”
“The heliport beacon shall emit repeated series of equispaced short duration white flashes” and “shall be located on or adjacent to the heliport preferably at an elevated position and so that it does not dazzle a pilot at short range.”

ICAO Annex 14 Volume II