Yes, that's the correct way; the measurement is in half points.
In a docx, you'd have something like:
<w:rPr>
<w:sz w:val="28" />
</w:rPr>
ECMA 376 spec on @sz defines the unit as ST_HpsMeasure (Measurement in Half-Points)
Its the same with the binary doc format, which HWPF supports. If you look at [MS-DOC], you'll see it also specifies the size of text in half-points.