Introduction to Processing Steps
Processing Steps has first been published in a specification of the Ghent PDF Workgroup which then has submitted it to ISO to become an ISO standard. It has been further developed there into ISO 19593‐1, which - when this article was written in April 2018 - was in a final voting and scheduled for publication thereafter.
In it's essence, Processing Steps standardizes the way how production information related to processing steps other than the actual print process is encoded into PDF files. The means that is used are PDF layers (OCGs) and the Processing Steps standard defines how metadata may be attached to the OCG objects to identify the objects in an OCG as belonging to a certain processing step, e.g. a cut line, folding marks but also a white or varnish form or braille.
The standard defines syntax and semantic of the metadata. It also defines additional rules for objects on such layers and interdependencies to other objects. E.g. objects on a layer related to a cut line may only be vector objects or text (no images or smooth shades) and the must not be overlapped by print content.
ISO 19593-1 has a general part defining syntax and abstract rules and a concrete part that applies the general definitions to PDF files for packaging and label.
Processing Steps Metadata is organized in two hierarchical levels, "groups" (1st level) and "types". The application for packaging and label has 7 groups:
From which two, Structural and Positions must have types.
Custom values may be needed if none of the predefines values can be used.