// std_cxx1x::_3</code> for the local assembly function that specify
// cell, scratch data, and copy data, as well as the placeholder
// <code>std_cxx1x::_1</code> for the copy function that expects the
- // data to be written into the global matrix. On the other hand, the
- // implicit zeroth argument of member functions (namely the
- // <code>this</code> pointer of the object on which that member
+ // data to be written into the global matrix (for placeholder
+ // arguments, also see the discussion in step-13's
+ // <code>assemble_linear_system()</code> function). On the other
+ // hand, the implicit zeroth argument of member functions (namely
+ // the <code>this</code> pointer of the object on which that member
// function is to operate on) is <i>bound</i> to the
// <code>this</code> pointer of the current function. The
// WorkStream::run function, as a consequence, does not need to know