Proposal pursuant to discussions on the application of footnote 18 under Table 1 concerning tell-tale symbols and the use of colours to convey different meanings. ISO standard 2575-2004, para. 5.1. allows for the use of different colours to convey a change in the operating condition. This proposal would remove the current footnote 18 text and application of the footnote to telltales 2, 9-12, and 19 pending a decision on the proposal to apply a revised footnote to the master lighting switch (tell-tale 1). Paragraph 5.4.1.1. of UN R121 references ISO 2575-2004 which was developed to simplify the application of UN R121 when colour changes are adopted in other UN Regulations; however, OICA submits that the footnote which references ISO 2575-2004 in relation to specific lighting devices or systems creates a degree of confusion. (If approved, this proposal would likely impact Supplement 3 to the 01 series rather than Supplement 2 given that WP.29 at its November 2017 session adopted the proposal to add a telltale and symbols for “Accident Emergency Call System (AECS)” and to align UN R121 with the 07 series of amendments to UN Regulation No. 16 as Supplement 2 to the 01 series.)
43. Recalling discussions at the previous GRSG session on the handling of colour changes of controls, tell-tales and indicators, the expert from OICA presented ECE/TRANS/WP.29/GRSG/2018/6 as a long-term solution. He explained that the proposal aimed to remove the references in Table 1 to footnote 18 and to only keep the reference to standard ISO 2575:2004. GRSG noted study reservations by the experts from France and the United Kingdom. GRSG agreed to resume consideration of this subject at its next session.
49. The expert from OICA presented ECE/TRANS/WP.29/GRSG/2017/18 to clarify footnote 18 where tell-tales Nos. 1 and 19 were combined. Some experts were of the opinion that footnote 12 already offers that possibility. Following the discussion, the expert from OICA offered an alternative proposal GRSG-113-39 that simplifies the handling of colour changes of tell-tales and to remove footnote 18 and all references to it. The expert from France preferred to keep the existing text of footnote 18 and to only insert under symbol No. 1 a reference to footnote 18, as reflected in GRSG-113-42. GRSG agreed to go forward with a two-step approach and adopted ECE/TRANS/WP.29/GRSG/2017/18 as reproduced below.
| No. | Column 1 | Column 2 | Column 3 | Column 4 | Column 5 |
| Item | Symbol 2 | Function | Illumination | Colour | |
| 1. | Master lighting switch
|  1, 18 | Control | No | |
| Tell-tale 12 | Yes | Green |
50. The secretariat was requested to submit the proposal to WP.29 and AC.1 as draft Supplement 10 to the original series of amendments and Supplement 3 to the 01 series of amendments to UN Regulation No. 121 for consideration at their March 2018 sessions, subject to the endorsement of the Working Party on Lighting and Light Signalling (GRE) at its October 2017 session. (Note by the secretariat: At its seventy-eighth session, GRE endorsed the principles for amending UN Regulation No. 121 as proposed by GRSG.)
51. As a second step, GRSG requested the secretariat to distribute GRSG-113-39 with an official symbol, for consideration at the next GRSG session and to also circulate it all WP.29 Working Parties concerned.
| GRSG-113-39 | |
| GRSG-113-42 | |
| GRSG/2017/18 | |
| WP.29/2018/25 | |
| WP.29/2018/26 | |
| GRSG/2019/17 |