In The Unicode Standard, Tibetan script implementation is discussed in  Chapter 13 South and Central Asia-II: Other Modern Scripts.

The Tibetan script was first encoded in The Unicode Standard version 2.0. The script is encoded in the following block:

BlocksCharacter RangeAdded in Unicode VersionUnicode Chart
Tibetan 0F00..0FFF 2.0  U0F00.pdf

Subsequent to version 2.0, the following characters have been added to the Tibetan script:

CharactersUnicode VersionDocumentation
0F6A, 0F96, 0FAE..0FB0, 0FB8, 0FBA..0FBC, 0FBE..0FCC, 0FCF 3.0  
0FD0..0FD1 4.1  n2694.pdf  L2/04-007
0F6B..0F6C 5.1  n2985.pdf  L2/05-244
0FCE 5.1  n3011.pdf  L2/05-345
0FD2 5.1  n3032.pdf  L2/06-043
0FD3..0FD4 5.1  n3033.pdf  L2/06-044
0FD5..0FD8 5.2  n3268.pdf  L2/07-148
0F8C..0F8F 6.0  n3568.pdf  L2/09-032
0FD9..0FDA 6.0  n3569.pdf  L2/09-033

Documentation refers to  ISO Working Group and Unicode proposals

A number of proposals for its inclusion were submitted to the Unicode Technical Committee and WG2:

1992 The Tibetan proposal is a revision of the one in Unicode 1.0, Vol 1. ( Unicode Technical Report #2)

1995-06-21 Tibetan in ISO/IEC 10646-1 — Lloyd Anderson ( WG2 N1227)

1995-09-18 On the complexity of Tibetan character names — Michael Everson ( WG2 N1263.txt)

1997-12-08 Proposal to encode Tibetan Extensions in ISO/IEC 10646 — China, Ireland, United Kingdom ( WG2 N1660.htm, L2/98-024 (not online))

1998-05-27 Proposal for Tibetan extensions to the UCS — Lloyd Anderson, Robert Chilton, Tony Duff, Michael Everson, Christopher Fynn, Rick McGowan, Sam Sirlin, Kenneth Whistler, Валерий Умаков ( WG2 N1756,  L2/98-218)

1999-10-01 ISO 10646-1, Amd. #31 – Tibetan with correct code charts — SC2/WG2 ( WG2 N2130,  L2/99-352)

2000-01-31 Note on the script name "Tibetan" — The Orient Foundation ( WG2 N2218.doc,  L2/00-106)

2002-01-14 Character Properties for repetition marks — Kenneth Whistler ( L2/02-016)

2002-12-06 Proposal on Tibetan BrdaRten Characters Encoding — China NB ( WG2 N2558,  L2/02-455)

2003-01-22 Tibetan Script: Precomposed Tibetan (response to L2/02-455) — Andrew C. West ( L2/03-002)

2003-08-18 Unicode Tibetan in Tibetan (for info only) — Chris Fynn ( L2/03-268)

2003-09-18 Revised Proposal on Tibetan BrdaRten Character Encoding for ISO/IEC 10646 in BMP — China NB ( WG2 N2621)

2003-09-24 Comments on N2621 (Tibetan encoding additions) — Andrew C. West ( WG2 N2624,  L2/03-315)

2003-09-25 Comments on proposal N2621 (Tibetan encoding additions) — Steve Hartwell ( WG2 N2625.doc,  L2/03-316)

2003-09-30 Comments on N2621 — Robert Chilton ( WG2 N2635.doc,  L2/03-322)

2003-09-30 Comments on the difficulty of implementing "dynamically combining" model used in the encoding of Tibetan in the UCS - as raised in proposal N2621* from China. — Chris Fynn ( WG2 N2637.doc,  L2/03-325)

2003-10-01 Comments on N2621, Proposal to Encode Tibetan BrdaRten Characters — UTC / L2 position ( WG2 N2638,  L2/03-328)

2003-10-17 Clarification and explanation on Tibetan BrdaRten proposal — China N B ( WG2 N2661,  L2/03-392)

2003-10-20 Comments on N2661, clarification and explanation on Tibetan BrdaRten Proposal — UTC / L2 ( WG2 N2668.doc,  L2/03-368)

2003-10-20 China's Statement of BrdaRten ad hoc — China N B ( WG2 N2674,  L2/03-378)

2003-10-22 Comments on N2621, Proposal to encode Tibetan BrdaRten — Peter Constable ( L2/03-351)

2003-12-30 Proposal to encode two Bhutanese marks for Dzongkha — Michael Everson, Chris Fynn ( WG2 N2694,  L2/04-007)

2004-03-09 Indic scripts collation grouping; CTT suggestion — Kent Karlsson ( WG2 2716.doc,  L2/04-109)

2005-02-07 Issues in Representation of Indic Scripts in Unicode (Unicode Conference Presentation) — Om Vikas ( L2/05-063)

2005-02-14 Basic line breaking rules for Tibetan, Dzongkha, and Ladakhi — Asmus Freytag, Chris Fynn ( L2/05-073)

2005-09-04 Proposal to add four Tibetan characters for Balti to the BMP of the UCS — Michael Everson ( WG2 N2985,  L2/05-244)

2005-10-24 Proposal to encode three archaic Tibetan characters — Andrew C. West ( WG2 N3012,  L2/05-346)

2005-10-25 Comments on N2985 – Balti Tibetan additions — Andrew C. West ( WG2 N3010,  L2/05-338)

2005-10-27 Comments on: N3012 - Proposal to encode three archaic Tibetan characters — Christopher J. Fynn ( L2/05-347)

2005-11-03 Re: New Tibetan Proposals — Christopher Fynn ( L2/05-364)

2006-01-30 Proposal to encode one Tibetan astrological character — Andrew C. West ( WG2 N3011,  L2/05-345)

2006-01-30 Proposal to encode one Tibetan punctuation mark - see also L2/05-346; this splits and revises that proposal) — Andrew C. West ( WG2 N3032,  L2/06-043)

2006-01-30 Proposal to encode two archaic Tibetan punctuation marks - see also L2/05-346; this splits and revises that proposal) — Andrew West ( WG2 N3033,  L2/06-044)

2007-04-11 Proposal on Adding 3 Tibetan Characters and a symbol for ISO/IEC 10646 — China N.B. ( WG2 N3240,  L2/07-113)

2007-04-20 Comments on proposal N3240 — Christopher J. Fynn ( WG2 N3247,  L2/07-114)

2007-04-22 A response to N3240 (dated 2007-04-11), the National Proposal (China) entitled "Proposal on Adding 3 Tibetan Characters and a symbol for ISO/IEC 10646 in BMP" — Robert R. Chilton ( L2/07-124)

2007-05-09 Proposal to encode four religious characters in the Tibetan block of the UCS Michael Everson, Chris Fynn, Peter Scharf, Andrew West ( WG2 N3268,  L2/07-148)

2008-03-02 Criteria for the encoding of script-specific dandas — Unicode and US National Body ( WG2 N3457,  L2/08-118)

2008-08-09 Tibetan Chars in PR 122 — Chris Fynn ( L2/08-304)

2008-10-14 Proposal to add India specific annotation to Right facing Svasti Swaran Lata ( WG2 N3537.doc,  L2/09-060)

2009-01-24 Proposal to encode four Tibetan-Sanskrit letters used in Kalacakra texts — Andrew West, Christopher Fynn ( WG2 N3568,  L2/09-032)

2009-01-24 Proposal to encode two Tibetan annotation marks — Andrew West, Christopher Fynn ( WG2 N3569,  L2/09-033)

2011-07-28 A clear policy on encoding OM characters — Shriramana Sharma ( L2/11-308)

2012-07-31 Indic Scripts in Unicode — Eric Muller ( L2/12-289)

2014-02-05 A bag of suggested improvements to Unicode’s provisional Indic properties — Roozbeh Pournader, Behdad Esfahbod ( L2/14-065)

2014-05-08 Improvements requested for Unicode Indic properties — Roozbeh Pournader ( L2/14-126)

2017-04-17 Request for editorial updates to Indic scripts — Srinidhi A, Sridatta A ( L2/17-098)

Recommendations to UTC #152 July-August 2017 on Script Proposals ( L2/17-255) (See point 7.)