Check it:

http://www.omniglot.com/writing/somali.htm

You could ask Saki Mafundikwa, the author of "Afrikan Alphabets".

hhp

Generally speaking, the Latin orthographies of southern and eastern African languages tend to be simpler than central and western orthographies, and use very few diacritics or special letters. See http://www.culturalorientation.net/somali/slang02.html for an overview of the official, 1972 orthography.