Note the NPS arrowhead logo's official Pantone/RAL colors

Unrelated to anything the app renders, but the doc already collects
NPS-ecosystem color facts and this came up while sourcing colors
for a 3D print of the shield.

docs/nps-resources.adoc

@@ -286,6 +286,50 @@ own work (a map viewer, not a publisher of NPS-branded content):
   resource — included here only because it was shared alongside the
   typography notes above.
 
+== Arrowhead (shield) logo colors
+
+Unrelated to anything this app renders — noted here only because it came up
+in conversation (wanting exact colors to 3D-print the NPS arrowhead) and
+this doc is already the dumping ground for NPS-ecosystem color/graphic-identity
+facts. Per NPS's own graphic identity standards (Harpers Ferry Center), the
+arrowhead uses three official Pantone spot colors plus white:
+
+[cols="2,2,1,1"]
+|===
+| Element | Pantone | Hex (converted) | Nearest RAL Classic
+
+| Mountain
+| Dark Rust, PMS 1615 C
+| `#8b4720`
+| RAL 2013 Pearl orange (`#923E25`)
+
+| Sky
+| Medium Rust, PMS 1605 C
+| `#a65523`
+| RAL 8023 Orange brown (`#A45729`)
+
+| Trees / grass
+| Dark Green, PMS 553 C
+| `#284734`
+| RAL 6012 Black green (`#2F3D3A`)
+
+| Bison, lake, snowfield, type
+| White
+| `#ffffff`
+| RAL 9016 Traffic white (`#F1F1EA`) — RAL has no pure white
+|===
+
+Hex values are third-party Pantone→RGB conversions, not something NPS
+publishes directly (their style guide only specifies PMS codes). RAL codes
+are the closest match by RGB distance against the RAL Classic chart — same
+caveat, not an official NPS-endorsed mapping, just the nearest available
+code for filament/paint shopping. Source: NPS Graphic Identity and Style
+Guides (https://www.nps.gov/subjects/hfc/nps-graphic-identity-and-style-guides.htm),
+FAQs About Arrowhead Artwork
+(https://www.nps.gov/subjects/hfc/faqs-about-arrowhead-artwork.htm). Use of
+the arrowhead symbol itself is controlled by law/regulation/policy — see
+the FAQ page before printing/distributing anything bearing it.
+
 == NPMap4 (the older, Leaflet-based generation)
 
 https://www.nps.gov/lib/npmap.js/4.2.1/ — predecessor to npmap5,