A CRI may also do training towards a class rating, for example someone who hold a ML rating and wishes to add a SEP or SSEA or vice versa.
If by "ML" you mean microlight then the above is incorrect.
A JAR-FCL CRI can only provide training in SEP to a person who holds a JAR-FCL licence.
If you have the appropriate type ratings you may teach for the single engine turbine rating and any SPA multi engine turbine ratings.
If only it was that simple!!
I recomend that JAR-FCL is the first thing that should be read. Particular attention should be made to the requirements that every CRI has to meet - (experience, training and test) before being able to teach on another type or class.
Regards,
DFC