Hebrew calendar cheat sheet

This post is largely for my own benefit, but I figured it might be interesting to others too, in terms of what you need to think about when coding against the Hebrew calendar. Currently I'm trying to work out what it means to add a year to a date in the Hebrew calendar, at which point it's useful to have some reference tables.

Month names

There are two month numbering systems, which Noda Time calls Civil and Scriptural. In leap years, the number/name mapping in the civil numbering system is offset for the second half of the year, due to Adar being split into Adar I and Adar II.

Number	Scriptural	Civil (non-leap)	Civil (leap)
1	Nisan	Tishri	Tishri
2	Iyar	Heshvan	Heshvan
3	Sivan	Kislev	Kislev
4	Tamuz	Tevet	Tevet
5	Av	Shevat	Shevat
6	Elul	Adar	Adar I
7	Tishri	Nisan	Adar II
8	Heshvan	Iyar	Nisan
9	Kislev	Sivan	Iyar
10	Tevet	Tamuz	Sivan
11	Shevat	Av	Tamuz
12	Adar / Adar I	Elul	Av
13	Adar II		Elul

(Heshvan is sometimes lengthened to Marcheshvan; it's also called Cheshvan. Heshvan is the version in CLDR, which is why I've used it here. Other month names have similar variations, e.g. Tishri vs Tishrei. These are only English versions of Hebrew names, of course.)

Sample years

In unit tests it's useful to have some sample data for specific situations. Here's the data for a complete leap cycle of 19 years. (This period maps to years 1639 to 1659 in the Gregorian calendar.)

Year	Leap?	Days in Cheshvan	Days in Kislev
5400	No	29	30
5401	No	29	29
5402	Yes	30	30
5403	No	29	30
5404	Yes	29	29
5405	No	30	30
5406	No	29	30
5407	Yes	30	30
5408	No	29	29
5409	No	30	30
5410	Yes	29	30
5411	No	30	30
5412	No	29	29
5413	Yes	29	30
5414	No	30	30
5415	Yes	30	30
5416	No	29	29
5417	No	29	30
5418	Yes	30	30
5419	No	30	30