I need help in determining the location of the following definition of printed circuit board thickness:
"Laminate Thickness - Thickness of the metal-clad base material, single- or double-sided, prior to any subsequent processing."

I don't need help in determining what this means, I know this means the thickness of the PWB including the copper, prior to plating or other processing.
What I need help with is: which IPC Standard or standards contains this definition?

Dean