LaTeX float controls - what is the denominator of the fraction macros?

Question

I'm looking in Section C.9 of the LaTeX manual (pages 199 and 200). LaTeX defines a few macros to control the float placement algorithm, namely, \topfraction, \bottomfraction, and \textfraction. The macro \topfraction, for example, defines "The maximum fraction of the page that can be occupied by floats at the top of the page." The text of the manual is not clear as to what the "page" is for these macros.

My question is this: is the denominator of these fractions the length \paperheight, the length \textheight, or something else?

Thanks in advance.

Answer 1

It's a fraction of \textheight

Answer 2

They are "fractional numbers": the default value of \textfraction is 0.2. This means that at least 20% of the page should be filled with text.

So, to answer mathematically your question, the denominator is 1.