South-East Asian holidays rules can come in 3 types, based on some Full Moon day, or Lunar month day rudimentary calculation (similar to that used for the Burmese calendar), or based on specific rules for specific holidays.
That Luang Festival, Laos
Makha Bucha, Thailand
This rule type is based on the models described in the book The Calendrical Systems of Mainland South-East Asia, by J.C. Eade, published as part of the "Handbuch der Orientalistik" series.
See also: Recurrence Rules Options.