Emoji drawings used sparingly on the charts (owner, Q7: emoji "wisely, and conservatively ... in very helpful places").
Source: Noto Emoji, https://github.com/googlefonts/noto-emoji (2D/svg), downloaded 2026-10-06.
Licence: the project README says "Tools and most image resources are under the Apache license, version 2.0";
         its root LICENSE file (copied here as LICENSE_noto-emoji.txt) currently carries the SIL Open Font License 1.1 text.
         Both allow use, embedding and redistribution with the notice kept.
Used:  emoji_u1f4d6.svg  📖 key verse
       emoji_u2696.svg   ⚖️ scholars differ (disputed points)
       emoji_u1f552.svg  🕒 hour by hour
Why SVG drawings and not an emoji font: the PDF must embed only the series fonts (no Windows system fonts); SVG stays sharp.