2.1.168 Part 1 Section 17.4.67, tcFitText (Fit Text Within Cell)
a. The standard defines no special behavior for a cell containing text with line breaks.
In Word, the text in the first paragraph in the cell is fit, but subsequent paragraphs are not.
b. The standard states that inter-character spacing shall be reduced to fit text.
In Word, the horizontal size of non-space characters is also reduced to fit text.