I find this situation arising from time to time:
There's an ambiguous phrase Z with multiple possible meanings, X and Y (for illustration).
If the author meant X, a reasonable or necessary choice of phrasing is Z.
If the author meant Y, they could (and hence would) have written the phrase differently in order to avoid ambiguity.
Therefore I conclude that the author does not mean Y, and hence means X.
I find it particularly important to be aware of this in technical writing: you need to write in the expected way.
I'm just after a name for this process...
Question: What's this inference process called?
There is a 12-page limit which could include references.
I infer that the page limit does not include references (or at least, it doesn't always include references), since if it did, they would have simply written:
There is a 12-page limit which includes references.
This also arose recently in my Chinese.SE question with the example:
I have two sisters
Without further inference, the above could mean older and/or younger sisters. However, if I meant anything other than "one older and one younger", I would have said either:
I have two older sisters
I have two younger sisters
Thus we infer I have one older and one younger sister.