The "integer projective line" wraps around, and after -1 there is another 0 again, something like

..., 0, 1, 2, 3, ..., ∞, ..., -3, -2, -1, 0, 1, 2, 3, ..., ∞, ..., -3, -2, -1, 0, 1, 2, 3, ..., ∞, ..., -3, -2, -1, ...

where all the repetitions of a number are equivalent. In particular, you can not define a "<".

The example was

[stop], 0, 1, 2, 3, ..., ∞, ..., -3, -2, -1, [stop]

where you can define "<". This example is more similar to the temperature classification in the article in Wikipedia. You can pass through infinity, but you can't pass through 0. (Perhaps to be more similar, we should remove 0.)