Numbers outside of the map [still cluttered]

REQUIREMENTS.md

@@ -119,8 +119,21 @@ a physical pen plotter.
   recorded positions from the surrounding area, not fabricated extrapolation.
 - Keep the map background within its requested bounds and provide space in the
   SVG for the extended tracks and their labels.
+- Place flight index numbers entirely outside the map border, within the
+  extension margin, near a track entry or exit point. Use vector leader lines
+  to associate labels with their tracks, including tracks entirely inside the
+  map. Avoid overlapping index labels and report insufficient margin space
+  rather than placing numbers inside the map.
 - Identify each flight track with its date, time, callsign or flight number when
   available, and average reported barometric (pressure) altitude in metres.
+- In the printed flight legend, show the date and time once per flight, using
+  the midpoint between the track's in-map start and end times in UTC. Label
+  altitude as "Alt", without "Baro". Retain full start/end times and altitude
+  source in SVG metadata.
+- Arrange flight legend entries in two balanced columns, reading down the left
+  column followed by the right, with shared headings and attribution spanning
+  the page. Reserve space based on the column row count and reject entries
+  that do not fit rather than overlapping or truncating them.
 - Do not present an OpenSky callsign as a verified passenger-facing flight
   number. Callsign-to-flight-number lookup is not required for the initial
   version.