Module metadata 

Per-layer metadata (Optional Content Groups).

Defined in ISO 32000-2 §8.11.2 (the OCG dictionary itself) and §8.11.4.4 (the /Usage sub-dict, which describes the contexts — view, print, export — in which the layer is meaningful).

Phase 1 is document-wide enumeration: produce one Layer record per OCG referenced from the catalog’s /OCProperties /OCGs array. Visibility defaults come from the default configuration’s /OFF array; locked state from /Locked. Hierarchy (/Order) and alternate configurations live in Phase 2.

Structs

CreatorInfo

/CreatorInfo sub-dict — authoring application + subtype hint.

ExportUsage

/Export sub-dict.

LanguageUsage

/Language sub-dict.

Layer

One Optional Content Group (PDF “layer”).

LayerUsage

Hints from the OCG /Usage sub-dict.

PrintUsage

/Print sub-dict.

UserUsage

/User sub-dict — user/group ownership.

ViewUsage

/View sub-dict.

ZoomUsage

/Zoom sub-dict — visibility range.

Enums

LayerIntent

/Intent on an OCG, declaring which audiences the layer is for.

PageElementSubtype

/PageElement /Subtype value — role of the layer on the page.

UsageState

Usage state — /ON or /OFF.

Functions

parse_layer

Parse one OCG dict into a Layer.

parse_layers

Walk the catalog’s /OCProperties /OCGs array and produce one Layer per OCG.

parse_usage_dict

Parse an entire /Usage dict into a LayerUsage.