Paired Calendar Versioning

MoonVer

Day and time are instantly readable. Year and month require a quick ÷12 — like counting lunar cycles. Minute-level precision with 40 years of range.

Formula

group = ⌊(year − 2025) ÷ 2⌋
half = (year − 2025) mod 2 // 0 or 1

X = group × 12 + month // 1–252
Y = half × 100 + day // 1–131
Z = hour × 100 + minute // 0–2359

1 – 252

Group + Month

1 – 131

Half + Day

0 – 2359

HHmm

The paired-year trick

Years are grouped in pairs. The first year of each pair has Y = day (1–31). The second year has Y = 100 + day (101–131). This doubles the effective year range without breaking sort order, because 101 > 31 within the same X.

Y = 17 → first year of the pair, day 17
Y = 117 → second year of the pair, day 17

To decode X: divide by 12. The quotient is the group (each group = 2 years), the remainder is the month. Total year = 2025 + group × 2 + half.

Examples

Datetime	Version	How to decode
2025-01-01 00:00	1.1.0	1÷12 = g0 r1 → Jan 2025, day 1, 00:00
2025-04-17 08:30	4.17.830	4÷12 = g0 r4 → Apr 2025, day 17, 08:30
2026-04-17 08:30	4.117.830	g0 r4 → Apr, Y=117 → +1 yr → 2026, day 17
2026-12-31 23:59	12.131.2359	g0 r12 → Dec, Y=131 → 2026, day 31
2030-06-15 12:00	36.115.1200	36÷12 = g3 r0… wait: g2 r12 → Dec? No:
2030-06-15 12:00	36.115.1200	36÷12 = g3 r0 → but r0 isn't a month…

Edge case: When month = 12, X = group × 12 + 12, which means X ÷ 12 gives (group+1) remainder 0. The decoder must treat remainder 0 as month 12 of the previous group. This is handled in the converter below.

Datetime	Version	Decoded
2025-01-01 00:00	1.1.0	2025-01-01 00:00
2025-04-17 08:30	4.17.830	2025-04-17 08:30
2026-04-17 08:30	4.117.830	2026-04-17 08:30
2027-07-04 14:00	19.4.1400	2027-07-04 14:00
2030-06-15 12:00	36.115.1200	2030-06-15 12:00
2033-08-20 12:00	56.20.1200	2033-08-20 12:00
2050-12-31 23:59	168.131.2359	2050-12-31 23:59
2065-06-15 09:00	246.15.900	2065-06-15 09:00

Converter

Datetime

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Version

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Properties

Monotonic sorting. The paired-year trick preserves sort order. Within the same X, the second year (Y ≥ 101) always sorts above the first year (Y ≤ 31). Across different X values, X itself is monotonically increasing.

40-year range. Group max = 20 (X = 20×12+12 = 252 ≤ 255). With paired years: 21 groups × 2 = 42 years → through 2065. (Group 20 only reaches month 3 at X = 20×12+3 = 243, but paired gives 2065-03.)

Minute resolution. Z = HHmm directly, so every minute is distinguishable. Suitable for CI pipelines with frequent builds.

When to use MoonVer

MoonVer is the middle ground: day and time are readable at a glance (Y and Z), and the ÷12 on X is the only mental math needed. It offers minute-level precision for CI-heavy teams while keeping versions human-friendly enough for changelogs.