Accidental Press Mark: philatelic term for an accidental press mark
Shifted Press Mark: deviation from the intended press mark position
Split Press Mark: shifted press mark split on multible postage stamps
Missing Press Mark: shifted press mark which did not reach a stamp field
Press Mark Plate With Accidental: press mark from a caused by an accidental damaged printing form
Light Press Mark: clear but too light press mark
Strong Press Mark: clear but too strong press mark