-- create cdef statement
_tif( _args, "CDEF:%s_stk=%s_nnl,%s_stk,+", source.sname, source.sname, prev )
_tif( _args, "CDEF:%s_plot=%s_avg,%s_stk,+", source.sname, source.sname, prev )
-- create cdef statement
_tif( _args, "CDEF:%s_stk=%s_nnl,%s_stk,+", source.sname, source.sname, prev )
_tif( _args, "CDEF:%s_plot=%s_avg,%s_stk,+", source.sname, source.sname, prev )