I just spent far too long with someone at the graduate office trying to get a concrete understanding of how they define double spacing. I tried my best to explain that I cannot just put an extra »line« between each line of my document.
All information I have been able to obtain elsewhere seems to indicate that what they really want, but do not seem to know it, is one and a one-half line spacing. That is in LaTeX you would set
\baselinestretch to 1.5. I am almost certain that this is what I should be doing, but the woman seemed to think that I wanted there to be twice as much space between baselines.
I tried to take the approach of getting concrete and asking that if I used a 10pt font, what should the measurement be between the bottom of one line and the next. However, to my surprise the woman I spoke with claimed that they do not actually measure this, they just look at it and »know«.
So we agreed that I would just fax her a sample and she would let me know whether it looked correct.
Surprisingly, the definition of double spacing is something that the Chicago Manual of Style does not address.