Marking/coloring a line inside a pdf standardized?

[mattad]

I can mark a line inside a pdf document with e.g. red background color.

Is this colorization standardized by pdf spec?
As far as I can some other pdf viewers recognize this marking.
But again: Is this standardized or just a proprietary feature (of some pdf developers)?

Matt

[Paul - PDF-XChange]

Hi Matt,

I can mark a line inside a PDF document with e.g. red background color.

If you are using PDF-Xchange to do this then yes it is compatible. All the Tools in the Viewer, in fact any action you take using the Viewer will result in a 100% compatible PDF. We do not offer any tools or functions that are not compatible.

hth