Example ~/.ctags file that gives support for Scala and XML

.ctags

--exclude=*html
--exclude=*.jar
--exclude=*.class
--exclude=*.erl
--exclude=*.hrl
--exclude=*.fxs
-R
--langdef=xml
--langmap=xml:.xml
--regex-xml=/<([a-zA-Z0-9]+)[^\/]*>/\1/t,tagname/
--langdef=scala
--langmap=scala:.scala
--regex-scala=/class ([a-zA-Z0-9]+)/\1/c,class/
--regex-scala=/object ([a-zA-Z0-9]+)/\1/c,object/
--regex-scala=/def ([a-zA-Z0-9]+)\(/\1/d,def/
--regex-scala=/val ([a-zA-Z0-9]+)/\1/v,val/
--regex-scala=/var ([a-zA-Z0-9]+)/\1/a,var/