What do P, NP, FS, O in timing table mean?

P stands for “preset mode” and is the preferred setting.
NP is ""Non Preset"" mode that the monitor supports and image can be displayed.
FS: Fail Save Mode. The image can still be displayed but may not be able to displayed correctly because it’s out of range. ""Out of Range"" will be shown.
O: Out of Range. The monitor does not support, and no picture would be shown.
Therefore, the resolution with P is the preferred setting.