In The Unicode Standard, Tai Tham script implementation is discussed in  Chapter 16 Southeast Asia.

The Lanna script was encoded in The Unicode Standard version 5.2, under the name Tai Tham. The script is encoded in the following block:

BlocksCharacter RangeAdded in Unicode VersionUnicode Chart
Tai Tham 1A20..1AAF 5.2  U1A20.pdf

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

1992-11-25 Tai Lu (Chieng Mai, Northern Thai) — Rick McGowan ( Unicode Technical Report #3 R2)

1999-07-20 Unicode Technical Report #3: Early Aramaic, Balti, Kirat (Limbu), Manipuri (Meitei), and Tai Lü scripts — Rick McGowan, Michael Everson ( WG2 N2042,  L2/99-245)

2004-06-28 Lanna Unicode: A Draft Proposal — Martin Hosken ( L2/04-351)

2005-04-21 Lanna Unicode: A Proposal — Martin Hosken ( L2/05-095)

2005-07-15 Towards a Computerization of the Lao Tham System of Writing — Gregory Kourilsky, Vincent Berment ( L2/05-166)

2005-08-02 Lao Tham in Terms of Lanna: a response to L2/05-166 from L2/05-095 — Martin Hosken ( L2/05-188)

2006-08-06 Proposal for encoding the Lanna script in the BMP of the UCS — Michael Everson, Martin Hosken ( WG2 N3121,  L2/06-258)

2006-09-20 Response to N3121R: Proposal for encoding the Lanna script in the BMP of the UCS — Ngwe Tun ( WG2 N3159,  L2/06-311)

2006-09-22 Opinions on N3121-Lanna script — China N.B. ( WG2 N3161,  L2/06-319)

2006-09-27 Lanna Ad Hoc Report — Chen Zhuang, Michael Everson, Martin Hosken, Wei Lin-Mei ( WG2 N3169,  L2/06-320)

2007-03-21 Revised proposal for encoding the Lanna script in the BMP of the UCS — Michael Everson, Martin Hosken, Peter Constable ( WG2 N3207,  L2/07-007)

2007-04-03 Proposing on Encoding Old Tai Lue — China N.B. ( WG2 N3238,  L2/07-101)

2007-04-11 Response to Chinese contribution N3238, “Proposing on Encoding Old Tai Lue” — Irish and UK National Bodies ( WG2 N3239,  L2/07-098)

2007-09-06 Comments on Lanna encoding in FPDAM4 — China N.B. ( WG2 N3313,  L2/07-307)

2007-09-10 Response to N3313 — Martin Hosken ( WG2 N3342,  L2/07-316)

2007-09-19 Ad hoc report on Lanna — WG2 ( WG2 N3346,  L2/07-319)

2007-12-20 Tai Tham ad-hoc meeting announcement 21-22 Jan 2008, Payap University, ChiangMai, Thailand — WG2 ( WG2 N3374,  L2/07-420)

2008-01-28 Tai Tham Subjoined Variants — Martin Hosken ( WG2 N3384,  L2/08-073)

2008-04-18 Tai Tham Ad-hoc Meeting Report — Peter Constable ( WG2 N3379,  L2/08-037)

2011-04-18 Proposal to change grapheme extending properties of various characters — Martin Hosken ( L2/11-114)

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 (two text file appendices are included) — Roozbeh Pournader ( L2/14-126)