Summary

gerbv currently skips Gerber X2 attributes (%TF%, %TA%, %TO%, %TD%) with a NOTE-level message. These are metadata extensions to RS-274X that don't affect rendering but carry useful information about what features represent.

X2 Attribute Types

• %TF (File) — file-level metadata: generation date, project name, creator tool, layer function (e.g. copper top, solder mask bottom)
• %TA (Aperture) — aperture properties: function (via pad, SMD pad, conductor), drill tolerance
• %TO (Object) — object context: component refdes, pin number, net name
• %TD (Delete) — clear a previously set attribute

Potential Uses

Parsing these would enable features like:

• Display component refdes/pin/net on hover or click
• Automatic layer identification (copper, mask, silk, paste) from %TF.FileFunction
• Filter or highlight by net name
• BOM cross-referencing from %TO.C (component) attributes
• Export netlist or component placement data extracted from Gerber X2 metadata

Current Behavior

Attributes are detected and skipped gracefully — geometry renders correctly since X2 is backwards-compatible with RS-274X. The skip messages are at NOTE level, which is appropriate.

Scope

This would involve:

1. Data model for attribute state (file attributes are global, aperture/object attributes follow a stack-like set/delete lifecycle)
2. Parser updates in gerber.c to store rather than skip the attributes
3. UI to surface the information (tooltips, info panel, layer properties)

Opening for discussion — interested to hear if others would find this useful and what subset of X2 would be most valuable to start with.