A Stelliums natal comparison begins with two separate nativities. Each saved chart retains its own birth data, Ascendant, Midheaven, sect, seven planets, Whole Sign houses, and provenance. The outer ring is a visual comparison layer, not a new chart and not a blended house frame.
What the historical source establishes
Ptolemy explicitly turns to both nativities in Tetrabiblos IV.5 and compares configurations among their luminaries. That passage is a real cross-nativity precedent. Dorotheus Book II discusses marriage within nativities and supplies traditional trine, square, opposition, and sextile doctrine, but it does not document the complete modern seven-by-seven interface used here.
Governed worked example
Worked example: two separate nativities, two exact contacts
In the frozen teaching fixture, Chart A has the Sun at 10 degrees Aries. Chart B has the Sun at 12 degrees Leo and the Moon at 11 degrees Gemini. Chart B Sun forms a sign-based trine to Chart A Sun with 2 degrees deviation from exact; Chart B Moon forms a sign-based sextile to Chart A Sun with 1 degree deviation. Chart A and Chart B house numbers are still calculated from their own Ascendants.
- Confirm authorization to use both birth records.
- Verify both saved calculations and keep their provenance visible.
- Read the complete 49-pair matrix for sign eligibility before sorting eligible contacts by exact deviation.
- Keep each planet in its own natal house; do not read Chart B through a fabricated shared house frame.
- Treat any interpretation as accountable human synthesis rather than a score or promised outcome.
Why phase and scoring are absent
Applying and separating phase requires motion through time. Two natal positions are fixed records, so Stelliums does not assign phase between them. Exact deviation measures geometry only. It is not a strength score, favorable percentage, or proof of a relationship outcome.