PDF form field rectangle out of page coordinates

Hi,

recently i came across a PDF file which had a (text) form field with the following rectangle coordinates:

LowerLeft:  170;850

UpperRight: 475;862

The page itself had: 595;841 whereas MediaBox=CropBox=BleedBox=TrimBox.

Thus the y coordinate is out of the page so to speak.

The adobe reader displays the field at the upper top of the page but within the boundaries of the page.

Maybe it does correct/fix it?

My question is:

1.) Is that pdf spec compliant? (I did a quick search however couldn't find anything about it)

2.) Is that PDF/A-1 compliant (if that makes a difference)?

Thanks,

ToM