cusparseSpMV - CUSPARSE_FORMAT_COO - different results in different runs

In the documentation, Section 14.6.6, under cusparseSpMV(), it says the following about using COO format sparse matrix:
May produce slightly different results during different runs with the same input parameters

What is the reason behind different results from different runs?
Is the maximum difference quantified? Or is it the case that just the last decimals vary?