HAM SIGN MAI LANG KAI is challenging
  due to its wide range of behaviours. It can behave as a spacing
  final character (as in modern Tai Khün fonts) to a repha-like
  character, the old-fashioned behaviour seen in Tai Khün, Thailand
  and Laos. The <a href="https://www.worldcat.org/search?qt=worldcat_org_all&amp;q=ISBN+974-8359-03-4"
  >MFL dictionary</a> shows an intermediate behaviour, where
  marks above the following base consonant cause it to be positioned
  within the previous syllable. This is th