What: The mca_base_var_* API replaces the mca_base_var_* API. A support layer for the old API currently resides in the trunk. I will remove the layer from the trunk and replace any remaining mca_base_param_* calls with their equivalents in the new API. The support layer will remain for the 1.7/1.8 release series.
When: This RFC is a heads up. I will remove the old API on Monday, May 20, 2013.