NRSI: Computers & Writing Systems
Terms of Reference for the SIL Private Use Area Committee
SIL PUA Pages
The SIL Private Use Area Committee (PUAC) is responsible to the International Director of Language Program Services (IDLPS) through the Director of the Non-Roman Script Initiative (NRSI) for developing policy for managed use of the Unicode Private Use Area (PUA)1 within SIL, and promoting this policy on behalf of SIL International for the benefit of the language communities and the people they serve. This includes:
In keeping with this purpose statement, the PUAC is responsible to produce the following deliverables, which shall be regularly updated and published for the SIL membership and Cooperating Organizations.
Scope of work
All assignments of characters in the PUA by SIL Entities and the Corporation are within the scope of the PUAC. Because of the technical nature of the work, a brief background statement is presented here before detailed statements of the scope of PUAC duties.
The Unicode Basic Multilingual Plane (BMP) consists of 64K code points, the majority of which are associated with the symbols and characters used in the standard orthographies of the world. Unicode reserves a range of 6400 code points in the BMP (U+E000–U+F8FF) for private-use by software developers and end users who need a special set of characters for their own purposes. There are also a number of additional private-use code points in the so-called “supplementary planes”, specifically “Plane 15” (U+F0000–U+FFFFF) and “Plane 16” (U+100000–U+10FFFF), which provide an additional 64K code points each.
By convention the PUA range within the Basic Multilingual Plane is divided into the Corporate Use Subarea (CUS) extending from U+F8FF downward and the End User Subarea (EUS), extending from U+E000 upward. Unicode suggests that characters intended for corporate wide usage, such as for software, be assigned to the CUS. The EUS is intended for individual use, such as for scratch allocations of character space. The boundary between these two areas is not defined so as to accommodate individual and corporate needs (Unicode 3.0 §13.5).
A de facto boundary does exist however—the region U+F000 to U+F0FF is used within Windows fonts to encode symbols. Hosken (1998) states in a proposal endorsed by CTC, “it would seem wise to avoid using this area.” This splits the PUA into two blocks. The lower block of 4096 code points (U+E000 to U+EFFF) encompasses the EUS. The upper block of 2048 code points (U+F100 to U+F8FF) encompasses the CUS.
Hosken’s 1998 proposal gives Entities freedom to assign characters in the lower PUA block, and the Corporation the right to assign characters to the upper PUA block. He also proposes that Entity assignments be mirrored in the PUA supplementary planes as a means of converting cleanly from any entity-specific encoding to a universal corporate-wide encoding. See Figure 1 (adapted from Hosken 1998).
Although the PUAC is not bound by Hosken’s proposal, it has served as the starting point for preliminary discussions of PUA policy. The following three principles found in Hosken’s proposal will form the basis for PUA policy in the future:
Determining SIL PUA policy
The committee, on the behalf of SIL International, will determine SIL corporate-wide PUA policy, including the extent of the Entity-controlled and Corporate-controlled portions of the PUA.
Managing the Corporate-controlled PUA area
The committee will review submissions of characters from SIL Entities and Cooperating Organizations to decide if they should be assigned code points in Corporate BMP PUA area. The committee will ensure that every character assigned by SIL Entities to the Entity-controlled portion of the BMP PUA that is reported to the committee and that does not exist elsewhere in the BMP has a corresponding code in Plane 15 or 16.
The committee will review and approve submissions of characters from SIL Entities and Cooperating Organizations (e.g. SIL Mexico Branch, NRSI, LSDev, FOBAI member organizations) for assignments in the Corporate BMP PUA area.
The committee may ask submitters for further information on proposed characters in order to make its decisions.
Providing mappings to corporate-wide assignments
The committee will ensure, and document, that there is a mapping between SIL Entity assignments reported to the committee and corporate-wide assignments. This will serve as a corporate-wide form of representation and the basis for tools that will allow easy interchange and conversion of data. The committee will not be required to perform this function for non-SIL Cooperating Organizations.
Making recommendations to Entities regarding PUA management
The committee will make recommendations to Entities regarding management of their PUA area. This will include but is not limited to:
Advising NRSI and LSDev regarding Unicode issues that relate to the PUA
The committee will advise NRSI and LSDev regarding Unicode issues that relate to the PUA. This will include but is not limited to:
Interfacing with SIL and other organizations regarding the PUA
The committee will be the point of contact within SIL and with other organizations regarding the PUA. This will include but is not limited to:
An informal mandate for a committee such as the Private Use Area Committee (PUAC) came from a motion passed by CTC in 1998, requesting that NRSI implement a plan for managed use of the Unicode private-use area within SIL. The management strategy that NRSI has proposed is outlined in a paper by M. Hosken 1998. The goal of this strategy is to maximize the freedom of SIL Entities (e.g. Areas, Branches, Departments) to implement needed characters while maintaining a central information repository to ensure consistency of field data and the ability to share and archive data within SIL. NRSI felt that a committee needed to be formed to hold itself accountable to the rest of the corporation because of the far-reaching implications of this strategy and because NRSI realizes its lack of total understanding in some areas of PUA and needs input from other domains.
In 2005, SIL International entered into a cooperative agreement to become an Operational Sponsor in charge of managing the PUA on behalf of the Forum of Bible Agencies International (FOBAI). This sponsorship requires the PUAC to receive requests from IFOBA member organizations about the proper use of Unicode for encoding the orthographies used in Scriptures and, when necessary, to add characters that are not in the Unicode standard to the SIL Corporate PUA.
The publication of these Terms of Reference constitutes the formal establishment of the Private Use Area Committee to undertake the activities outlined in this document on behalf of the IDLPS for the entire Corporation and non-SIL Cooperating Organizations.
The PUAC is accountable to the International Director of Language Program Services through the Director of NRSI. Each member of the PUAC is accountable individually to the Director, Coordinator or Department Head who appointed him or her to the committee. Reports from the PUAC and correspondence on major issues shall be directed to the Director of NRSI with copies to the IDLPS and the Director of Language Software Development (LSDev).
The IDLPS will approve the composition of the PUA committee. NRSI will have at least two members on the committee. The following people will have the right to nominate at least one member: Director of Language Software Development, the Language and Culture Archives Director, the International Linguistics Coordinator, and the International Literacy and Education Coordinator. The director of NRSI may appoint in consultation with the IDLPS up to three at-large members from SIL entities and Cooperating Organizations if it is felt that there is not enough non-NRSI participation.
The Directors or Department Heads designated by the IDLPS will appoint committee members for a term of no less than one year. Members will maintain an active status by keeping in contact with the other committee members as issues are discussed, and particularly when approval is requested on decisions. If a member does not maintain contact with the committee or participate in approval motions, the committee may ask the member’s Director or Department Head to replace the member or place the member on inactive status. A member may resign after giving notice to his/her Director or Department Head.
Most business will be conducted by email. Meetings or teleconferences may be scheduled on an ad hoc basis by mutual consent of the members. Informal meetings of a non-constituted sub-group of the committee are encouraged, but are not to make decisions for the committee as a whole.
Committee decisions may be made on a consensus basis without formal voting. However, any committee member may request a formal vote on any committee decision. A good faith effort needs to be made to contact all members of the committee before any formal decision is taken.
Selection and Responsibilities of Chair
The chair will be selected by majority vote of the committee’s active membership for a term of no less than one year. The chair will be responsible for:
The Chair may resign after giving one month’s notice to the committee.
Unicode Consortium. 1999. The Unicode Standard. Version 3.0. Reading, MA: Addison-Wesley.
Hosken, Martin. 1998. “PUA Corporate Strategy: A Discussion on the Organization of the PUA.” A paper delivered at SIL Computer Technical Conference, October 1998.
14-Jan-2010 Revisions of PUA functions based on changes in SIL internal structure.