In The Unicode Standard, Old Persian script implementation is discussed in  Chapter 11 Cuneiform and Hieroglyphs.

The Old Persian script was encoded in The Unicode Standard version 4.1. The script is encoded in the following block:

Blocks Character Range Added in Unicode Version Unicode Chart
Old Persian 103A0..103DF 4.1  U103A0

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

1992-10-20 Old Persian Cuneiform — Rick McGowan ( Unicode Technical Report #3 R2)

1997-09-18 Proposal to encode Old Persian Cuneiform in Plane 1 of ISO/IEC 10646-2 — Michael Everson ( WG2 N1639.htm, L2/97-269 (not online))

1999-07-23 Comments on proposals for the Universal Multiple-Octed Coded Character Set — Dr. W. Röllig (xlat. Küster) ( L2/99-224)

1999-10-04 Response to comments on the question of encoding Old Semitic scripts in the UCS (N2097) — Michael Everson ( WG2 N2133.htm)

2000-02-15 Scripts from the Past in Future Versions of Unicode — Carl-Martin Bunz ( L2/00-128)

2000-04-26 Further comments on historic scripts — Carl-Martin Bunz ( L2/00-153)

2000-12-21 Encoding Iranian Scripts in Unicode, Iranianist meeting report from Paris — Carl-Martin Bunz ( L2/01-007)

2002-12-03 Revised proposal to encode the Old Persian script in the UCS — Michael Everson ( WG2 N2545,  L2/03-097)

2003-09-18 Final proposal to encode the Old Persian script in the UCS — Michael Everson ( WG2 N2583,  WG2 N2583R,  L2/03-149)

2005-10-06 Cuneiform property inconsistencies — Ken Whistler ( L2/05-289)