P-Line was Discmania’s grippy premium blend from the Innova era, the Discmania name for what Innova sold as Pro. It’s retired.
It was sold as a plastic that reveals a mould’s character as it wears: grippier than C-Line, less durable, sitting between the baseline and the premium lines.
Two moulds are still listed in it. Anything you find in P-Line now is old stock or secondhand.