In this scientific article: [Label Filters for Large Scale Multilabel Classification](http://proceedings.mlr.press/v54/niculescu-mizil17a/niculescu-mizil17a.pdf) by Alexandru Niculescu-Mizil and Ehsan Abbasnejad, they use the notations P@1, P@5 and P@10 as the following table shows

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> [![enter image description here](https://i.stack.imgur.com/sEp1p.png)](https://i.stack.imgur.com/sEp1p.png)
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I was thinking that they were $p$-values at the beginning, but it somehow doesn't make sense. 

Could someone explain me what this notations mean?