focus morphemes

[Peter Bakker]

Dear typologists,

Many languages have special positions in the sentence for focussed
constituent. But how common is explicit morphological marking of
focus? The only languages I am aware of  are Aghem (NigerCongo,
Cameroon), Somali (AfroAsiatic) and Philippine languages (Tagalog),
perhaps also Malagasy (Austronesian) and  Akan (Kwa). Can anybody
tell me how common or uncommon this is or provide references to
literature or other languages?

Peter Bakker, Aarhus, Denmark