This is a book-chapter-verse (BCV) system for Bible references. Just as Strunk and White popularized, “Omit unnecessary words,” so this system omits unnecessary characters.

01.Genesis Ge
02.Exodus Ex
03.Leviticus Le
04.Numbers Nu
05.Deuteronomy De
06.Joshua Jo
07.Judges Jug
08.Ruth Ru
09.1-Samuel 1S
10.2-Samuel 2S
11.1-Kings 1K
12.2-Kings 2K
13.1-Chronicles 1Ch
14.2-Chronicles 2Ch
15.Ezra Ezr
16.Nehemiah Ne
17.Esther Es
18.Job Job
19.Psalms Ps
20.Proverbs Pr
21.Ecclesiastes Ec
22.Song-of-Solomon So
23.Isaiah Is
24.Jeremiah Je
25.Lamentations La
26.Ezekiel Eze
27.Daniel Da
28.Hosea Ho
29.Joel Joe
30.Amos Am
31.Obadiah Ob
32.Jonah Jon
33.Micah Mi
34.Nahum Na
35.Habakkuk Hb
36.Zephaniah Zp
37.Haggai Hg
38.Zechariah Zc
39.Malachi Ml
40.Matthew Mt
41.Mark Mk
42.Luke Lu
43.John Jh
44.Acts Ac
45.Romans Ro
46.1-Corinthians 1Co
47.2-Corinthians 2Co
48.Galatians Ga
49.Ephesians Ep
50.Philippians Php
51.Colossians Co
52.1-Thessalonians 1Th
53.2-Thessalonians 2Th
54.1-Timothy 1Ti
55.2-Timothy 2Ti
56.Titus Ti
57.Philemon Phe
58.Hebrews He
59.James Ja
60.1-Peter 1P
61.2-Peter 2P
62.1-John 1J
63.2-John 2J
64.3-John 3J
65.Jude Jue
66.Revelation Re

Prepending the book number, zero-padded, adds a little redundancy that also adds important information, conveyed in only two characters. Seeing the order in which the book appears in Bibles is very helpful to find the book in a codex.

Finally, zero-padding chapters and verses (as necessary) perfects sorting, e.g. 19Ps 001:1–6, 19Ps 100:1–5, 19Ps 102:01–28, 19Ps 119:001–176, 57Phe 1:01–25. 643J 1:01–14.