Blending

[Greg Bennett]

Hello there .. 
I am trying to experiment with the 4th, A, attribute of glColor to erase
lines, points, etc. 
Looking at Chapter 6 of the OpenGL Programming Guide, I see mention of
blending and its activation when using that attribute.
Specifically, Example 6-1 on P230 begins with
    glClearColor(1.0, 10., 1.0, 0.0);
    glBlendFunc(GL_ONE, GL_ONE);
    glEnable(GL_BLEND);

I can see the definitions of glBlendFunc and glEnable in the file
  funcs-gl-gles1-gles2.lisp
so I presume they are callable. It is the arguments which have me
tricked.

GL_ONE is defined as (1, 1, 1) on P228, GL_BLEND gets no mention that I
can find.

I would appreciate pointers to the calling sequences under cl-opengl of
the above 3 lines. I have to say that I can do some erasing without
calling glBlendFunc or glEnable, although what happens is a bit odd.

Perhaps there are examples/resources of which I am unaware which would
have saved me posting what may be a simple query to the list.

Thanks for any and all assistance, and for you patience.
Cheers /Greg Bennett